Third Revision — Includes blitter chip information .
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INTERNALS
The authoritative insider’s guide
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A Data Becker book published by
— ■ You Can Count On yf ^
Abacus Imiii Software
INTERNALS
The authoritative insider’s guide
By K. Gerits, L. Englisch, R. Bruckmann
A Data Becker Book
Published by
Abacus mana Software
Third Edition, January 1988
Printed in U.S.A.
Copyright© 1985,1986,1987, 1988 Data Becker GmbH
MerowingerstraBe 30
4000 Diisseldorf, West Germany
Copyright © 1985,1986,1987, 1988 Abacus Software, Inc.
5370 52nd Street, S.E.
Grand Rapids, MI 49508
This book is copyrighted. No part of this book may be reproduced, stored
in a retrieval system, or transmitted in any form or by any means,
electronic, mechanical, photocopying, recording or otherwise without the
prior written permission of Abacus Software or Data Becker, GmbH.
Every effort has been made to ensure complete and accurate information
concerning the material presented in this book. However, Abacus Software
can neither guarantee nor be held legally responsible for any mistakes in
printing or faulty instructions contained in this book. The authors will
always appreciate receiving notice of subsequent mistakes.
ATARI, 520ST, ST, TOS, ST BASIC and ST LOGO are trademarks or
registered trademarks of Atari Corp.
GEM, GEM Draw and GEM Write are trademarks or registered trademarks
of Digital Research Inc.
IBM is a registered trademark of International Business Machines.
ISBN
0-916439-46-1
Table of Contents
1
The Integrated Circuits
1
1.1
The 68000 Processor
3
1.1.1
The 68000 Registers
4
1.1.2
Exceptions on the 68000
7
1.1.3
The 68000 Connections
7
1.2
The Custom Chips
13
1.3
The WD 1772 Floppy Disk Controller
20
1.3.1
1772 Pins
20
1.3.2
1772 Registers
24
1.3.3
Programming the FDC
25
1.4
The MFP 68901
28
1.4.1
68901 Connections
28
1.4.2
The MFP Registers
32
1.5
The 6850 ACIAs
41
1.5.1
The Pins of the 6850
41
1.5.2
The Registers of the 6850
44
1.6
The YM-2149 Sound Generator
48
1.6.1
Sound Chip Pins
50
1.6.2
The 2149 Registers and their Functions
52
1.7
I/O Register Layout of the ST
55
2
The Interfaces
65
2.1
The Keyboard
67
2.1.1
The Mouse
71
2.1.2
Keyboard commands
74
2.2
The Video Connection
85
2.3
The Centronics Interface
88
2.4
The RS-232 Interface
90
2.5
The MIDI Connections
93
2.6
The Cartridge Slot
96
2.6.1
ROM Cartridges
97
2.7
The Floppy Disk Interface
99
2.8
The DMA Interface
101
3
The ST Operating System
103
3.1
The GEMDOS
106
3.1.1
Memory, files and processes
145
3.2
The BIOS Functions
152
3.3
The XBIOS
164
i
3.4
The Graphics
206
3.4.1
An overview of the line-A variables
227
3.4.2
Examples for using the line-A opcodes
230
3.5
The Exception Vectors
235
3.5.1
The line-F emulator
238
3.5.2
The interrupt structure of theST
240
3.6
The ST VT52 Emulator
245
3.7
The ST System Variables
250
3.8
The 68000 Instruction Set
258
3.8.1
Addressing modes
259
3.8.2
The instructions
263
3.9
The BIOS Listing
271
4
Appendix
463
4.1
The System Fonts
465
4.2
Alphabetical listing of GEMDOS functions
467
4.3
The blitter chip
469
4.3.1
The blitter registers
471
4.4
The Mega ST realtime clock
478
4.5
Blitter chip demonstration programs
479
Index
491
II
List of Figures
1.1-1
68000 Registers
5
1.2-1
GLUE
14
1.2-2
MMU
16
1.2-3
SHIFTER
17
1.2-4
DMA
19
1.3-1
FDC 1772
21
1.4-1
MFP 68901
29
1.5-1
ACIA 6850
42
1.6-1
Sound Chip YM-2149
49
1.6-2
Envelopes of the PSG
53
1.7-1
I/O Assignments
62
1.7-2
Memory Map
63
1.7-3
Block Diagram of the Atari ST
64
2.1-1
6850 Interface to 68000
68
2.1-2
Block Diagram of Keyboard Circuit
70
2.1. 1-1
The Mouse
72
2.1. 1-2
Mouse control port
74
2.1.2-1
Atari ST Key Assignments
84
2.2-1
Diagram of Video Interface
86
2.2-2
Monitor Connector
87
2.3-1
Printer Port Pins
88
2.3-2
Centronics Connection
89
2.4-1
RS-232 Connection
92
2.5-1
MIDI System Connection
95
2.6-1
The Cartridge Slot
96
2.7-1
Disk Connection
100
2.8-1
DMA Port
102
2.8-2
DMA Connections
102
3.4-1
Lo-Res-Mode
208
3.4-2
Medium-Res-Mode
209
3.4-3
Hi-Res-Mode
210
4.3-1
BLITTER
469
4.3.1-1
BLITTER BLOCK DIAGRAM
471
m
Chapter One
- .
The Integrated Circuits
_ /
1.1 The 68000 Processor
1.1.1 The 68000 Registers
1.1.2 Exceptions on the 68000
1.1.3 The 68000 Connections
1.2 The Custom Chips
1.3 The WD 1772 Floppy Disk Controller
1.3.1 1772 Pins
1.3.2 1772 Registers
1.3.3 Programming the FDC
1.4 The MFP 68901
1.4.1 68901 Connections
1.4.2 The MFP Registers
1.5 The 6850 ACIAs
1.5.1 The Pins of the 6850
1.5.2 The Registers of the 6850
1.6 The YM-2149 Sound Generator
1.6.1 Sound Chip Pins
1.6.2 The 2149 Registers and their Functions
1.7 I/O Register Layout of the ST
Abacus Software
Atari ST Internals
The Integrated Circuits
1.1 The 68000 Processor
The 68000 microprocessor is the heart of the entire Atari ST system. This
16-bit chip is in a class by itself; programmers and hardware designers alike
find the chip very easy to handle. From its initial development by Motorola
in 1977 to its appearance on the market in 1979, the chip was to be a
competitor to the INTEL 8086/8088 (the processor used in the IBM-PC and
its many clones). Before the Atari ST's arrival on the marketplace, there
were no affordable 68000 machines available to the home user. Now,
though, with 16-bit computers becoming more affordable to the common
man, the 8-bit machines won't be around much longer.
What does the 68000 have that's so special? Here’s a very incomplete list
of features:
16 data bits
24 address bits (16- megabyte address range!!)
all signals directly accessible without multiplexer
hassle-free operation of "old" 8-bit peripherals
powerful machine language commands
easy-to-leam assembler syntax
14 different types of addressing
17 registers each having 32-bit widths
These specifications (and many yet to be mentioned here) make the 68000
an incredibly good microprocessor for home and personal computers. In
fact, as the price of memory drops, you'll soon be seeing 68000-based 64K
machines for the same price as present-day 8-bit computers with the same
amount of memory.
3
Abacus Software
Atari ST Internals
1.1.1 The 68000 Registers
Let's take a look at 68000 design. Figure 1.1-1 shows the 17 onboard
32-bit registers, the program counter and the status register.
The eight data registers can store and perform calculations, as well as the
normal addressing tasks. Eight-bit systems use the accumulators for this,
which limits the programmer to a total of 8 accumulators. Our 68000 data
registers are quite flexible; data can be handled in 1-, 8-, 16- and 32- bit
sizes. Even four-bit operations are possible (within the limits of Binary
Coded Decimal counting). When working with 32-bit data, all 32 bits can
be handled with a single operation. With 8- and 16-bit data, only the 8th or
16th bit of the data register can be accessed.
The address registers aren't as flexible for data access as are the data
registers. These registers are for addressing, not calculation. Processing
data is possible only with word (16-bit) and longword (32-bit) operations.
The address registers must be looked at as two distinct groups, the most
versatile being the registers A0-A6. Registers A7 and A7' fulfill a special
need. These registers are used as the stack pointer by the processor. Two
stack pointers are needed to allow the 68000 to run in USER MODE and
SUPERVISOR MODE. Register A7 declares whether the system is in
USER or SUPERVISOR mode. Note that the two registers work "under"
A7, but the register contents are only available to the respective operating
mode. We'll discuss these operating modes later.
The program counter is also considered a 32-bit register. It is theoretically
possible to handle an address range of over 4 gigabytes. But the address
bits A24-A31 aren't used, which "limits" us to 16 megabytes.
The 68000 status register comprises 16 bits, of which only 10 bits are used.
This status register is divided into two halves: The lower eight bits (bits 0
to 4 proper) is the "user byte". These bits, which act as flags most of the
time, show the results of arithmetical and comparative operations, and can
be used for program branches hinging on those results. We'll look at the
user byte in more detail later; for now, here is a brief list:
BIT 0 = Carry flag BIT 1 = Overflow flag
BIT 2 = Zero flag BIT 3 = Negative flag
BIT 4 = extend flag
4
Abacus Software
Atari ST Internals
Abacus Software
Atari ST Internals
Bits 8-10, 13 and 15 make up the status register's system byte. The
remaining bits are unused. Bit 15 works as a trace bit, which lets you do a
software controlled single-step execution of any program. Bit 13 is the
supervisor bit. When this bit is set, the 68000 is in supervisor mode. This
is the normal operating mode; all commands are executed in this mode. In
user mode, in which programs normally run, privileged instructions are
inoperative. A special hardware design allows access into the other memory
range while in user mode (e.g., important system variables, I/O registers).
The system byte of the status register can only be manipulated in supervisor
mode; but there's a simple method of switching between modes.
Bits 8 and 10 show the interrupt mask, and run in connection with pins
IPL0-IPL2.
The 68000 has great potential for handling interrupts. Seven different
interrupt priorities exist, the highest being the "non-maskable interrupt";
NMI. This interrupt recognizes when all three IPL pins simultaneously read
low (0). If, however, all three IPL pins read high, there is no interrupt, and
the system operates normally. The other six priorities can be masked by
appropriate setting of the system byte of the status register. For example, if
bit 12 of the interrupt mask is set, while 10 and II are off, only levels 7, 6
and 5 (000, 001 and 010) are recognized. All other combinations from
IPL0-IPL2 are ignored by the processor.
6
Abacus Software
Atari ST Internals
1.1.2 Exceptions on the 68000
We've spoken of interrupts as if the 68000 behaves like other
microprocessors. Interrupts, according to Motorola nomenclature, are an
external form of an exception (the machine can interrupt what it's doing,
do something else, and return to the interrupted task if needed). The 68000
distinguishes between normal operation and exception handling, rather than
between user and supervisor mode. One such set of exceptions are the
interrupts. Other things which cause exceptions are undefined opcodes, and
word or longword access to a prohibited address.
To make exception handling quicker and easier, the 68000 reserves the first
IK of memory (1024 bytes, $000000-$0003FF). The exception table is
located here. Exceptions are all coded as one of four bytes of a longword.
Encountering an exception triggers the 68000, and the address of the
corresponding table entry is output
A special exception occurs on reset, which requires 8 bytes (two
longwords); the first longword contains the standard initial value of the
supervisor stack pointer, while the second longword contains the address of
the reset routine itself. See Chapter 3.3 for the design and layout of the
exception table.
1.1.3 The 68000 Connections
The connections on the 68000 are divided into eight groups (see Figure
1.1-3 on page 11).
The first group combines data and address busses. The data bus consists of
pins D0-D15, and the address bus A1-A23. Address bit A0 is not available
to the 68000. Memory can be communicated with words rather than bytes
(1 word=2 bytes=16 bits, as opposed to 1 byte=8 bits). Also, the 68000
can access data located on odd addresses as well as even addresses. The
signals will be dealt with later.
It's important to remember in connection with this, that by word access to
memory, the byte of the odd address is treated as the low byte, and the even
7
Abacus Software
Atari ST Internals
address is the high byte. Word access shouldn't stray from even addresses.
That means that opcodes (whether all words or a single word) must always
be located at even addresses.
When the data and address bus are in "tri-state” condition, a third condition
(in addition to high and low) exists, in which the pins offer high resistance,
and thus are inactive on the bus. This is important in connection with Direct
Memory Access (DMA).
The second group of connections comprise the signals for asynchronous
bus control. This group has five signals, which we’ll now look at
individually:
1) R/W (READ/WRITE)
The R/W signal is a familiar one to all microprocessors. This
indicates to memory and peripherals whether the processor is writing
to or reading data from the address on the bus.
2) AS (ADDRESS STROBE)
Every processor has a signal which it sends along the data lines
signaling whether the address is ready to be used. On the 68000, this
is known as the ADDRESS STROBE (low active).
3) UDS (UPPER DATA STROBE)
4) LDS (LOWER DATA STROBE)
If the 68000 could only process an entire memory word (two bytes)
simultaneously, this signal wouldn't be necessary. However, for
individual access to the low-byte and high-byte of a word, the
processor must be able to distinguish between the two bytes. This is
the task performed by UDS and LDS. When a word is accessed,
both strobes are activated simultaneously (active=low). Accessing
the data at an odd address activates the Lower Data Strobe only, while
accessing data at an even address activates the Upper Data Strobe.
Bit A0 from the address bus is used in this case. After every access
when the system must distinguish between three conditions (word,
even byte, odd byte), A0 determines how to complete the access.
LDS and UDS are tri-state outputs.
8
Abacus Software
Atari ST Internals
5) DTACK
The above signals (with the exception of UDS and LDS) are needed
by an 8-bit processor. DTACK takes a different path; DTACK must
be low for any write or read access to take place. If the signal is not
low within a bus cycle, the address and data lines "freeze up" until
DTACK turns low. This can also occur in a WAIT loop. This way,
the processor can slow down memory and peripheral chips while
performing other tasks. If no wait cycles are used on the ST, the
processor moves "at full tilt".
The third group of connections, the signals VMA, VPA and E are for
synchronous bus control. A computer is more than memory and a
microprocessor; interfaces to keyboard, screen, printer, etc. must be
available for communication. In most cases, interfacing is handled by
special ICs, but the 68000 has a huge selection of interface chips onboard.
For hardware designers we'll take a little time explaining these synchronous
bus signals.
The signal E (also known as 02 or phi 2) represents the reference count for
peripherals. Users of 6800 and 6502 machines know this signal as the
system counter. Whereas most peripheral chips have a maximum frequency
of only 1 or 2 mHz, the 68000 has a working speed of 8 mHz, which can
increased to 10 by the E signal. The frequency of E in the ST is 800 kHz.
The E output is always active; it is not capable of a TRI- STATE condition.
The signal VPA (Valid Peripheral Address) sends data over the
synchronous bus, and delegates this transfer to specific sections of the chip.
Without this signal, data transfer is performed by the asynchronous bus.
VPA also plays a role in generating interrupts, as we'll soon see.
VMA (Valid Memory Address) works in conjunction with the VPA to
produce the CHIP-select signal for the synchronous bus.
The fourth group of 68000 signals allows simple DMA operation in the
68000 system. DMA (Direct Memory Access) directly accesses the DMA
controllers, which control computer memory, and which is the fastest
method of data transfer within a computer system.
To execute the DMA, the processor must be in an inactive state. But for the
processor to be signaled, it must be in a "sleep" state; the low BR signal
9
Abacus Software
Atari ST Internals
(Bus Request) accomplishes this. On recognizing the BR signal, the
68000’s read/write cycle ends, and the BG signal (Bus Grant) is activated.
Now the DMA-requested chip waits until the signals AS, DTACK and
(when possible) BGACK are rendered inactive. As soon as this occurs, the
BGACK (Bus Grant Acknowledge) is activated by the requested chip , and
takes over the bus. All essential signals on the processor are made high; in
particular, the data, address and control busses are no longer influenced by
the processor. The DMA controller can then place the desired address on
the bus, and read or write data. When the DMA chip is finished with its
task, the BGACK signal returns to its inactive state, and the processor again
takes over the bus.
The fifth group of signals on the 68000 control interrupt generation. The
68000's "user's choice" interrupt concept is one of its most extraordinary
performing qualities; you have 199 (!) interrupt vectors from which to
choose. These interrupt vectors are divided into 7 non- auto- vectors and 192
auto-vectors, plus 7 different priority lines.
Interrupts are triggered by signals from the three lines IPLO to IPL2; these
three lines give you eight possible combinations. The combination
determines the priority of the interrupt. That is, if IPLO, IPL1 and IPL2 are
all set high, then the lowest priority is set ("no interrupt"). However, if all
three lines are low, then highest priority takes over, to execute a
non-maskable interrupt. All the combinations in between affect special bits
in the 68000's status register; these, in turn, affect program control,
regardless of whether or not a chosen interrupt is allowable.
Wait - what are auto- vectors and non-auto- vectors? What do these terms
mean?
If requesting an interrupt on IPL0-IPL2 while VPA is active (low), the
desired code is directly converted from the IPL pins into a vector number.
All seven interrupt codes on the IPL pins have their own vectors, though.
The auto- vector concept automatically gives the vector number of the IPL
interrupt code needed.
When DTACK, instead of VPA, is active on an interrupt request, the
interrupt is handled as a non-auto-vector. In this case, the vector number
from the triggered chip is produced by DTACK on the 8 lowest bits of the
data bus. Usually (though not important here), the vector number is placed
into the user- vector range ($40~$FF).
10
Abacus Software
Atari ST Internals
The sixth set of connections are the three "function code" outputs FCO to
FC2. These lines handle the status display of the processor. With the help
of these lines, the 68000 can expand to four times 16 megabytes (64
megabytes). This extension requires the MMU (Memory Management
Unit). This MMU does more than handle memory expansion on the ST; it
also recognizes whether access is made to memory in user or supervisor
mode. This information is conveyed to a memory range only accessible in
supervisor mode. Also, the interrupt verification uses this information on
the FC line. The figure below shows the possible combinations of
functions.
Figure 1.1-3
E£2 E £1 _ ECU
0 0 0
0 0 1
0 10
Oil
10 0
10 1
110
111
Status
unused
User-mode data access
User-mode program
unused
unused
Supervisor data access
Supervisor program
Interrupt verification
The seventh group contains system control signals. This group applies to
the input CLK and BERR, as well as the bidirectional lines RESET and
HALT.
The input CLK will generate the working frequency of the processor. The
68000 can operate at different speeds; but the operating frequency must be
specified (4, 6, 8, 10, or even 12.5 mHz). The ST has 8 mHz built in,
while the minimum operating frequency is 2 mHz. The ST's 8 mHz was
chosen as a "middle of the road" frequency to avoid losing data at higher
frequencies.
The RESET line is necessary to check for system power-up. The 68000's
uata page distinguishes between two different reset conditions. On
power-up, RESET and HALT are switched low for at least 100
milliseconds, to set up a proper initialization. Every other initialization
requires a low impulse of at least 4 "beats" on the 68K.
Here is what RESET does in detail. The system byte of the status register is
loaded with the value $27. Once the processor is brought into supervisor
11
Abacus Software
Atari ST Internals
status, the Trace flag in the status register is cleared, and the interrupt level
is set to 7 (lowest priority, all lines allowable). Additionally, the supervisor
stack pointer and program counter are loaded with the contents of the first 8
bytes of memory, whereby the value of the program counter is set to the
beginning of the reset routine.
However, since the RESET line is bi-directional, the processor can also
have RESET under program control during the time the line is low. The
RESET instruction serves this pupose, when the connection is low for 124
beats". It's possible to re-initialize the peripheral ICs at any time, without
resetting the computer itself. RESET time puts the 68000 into a NOP state
- a reset is unstoppable once it occurs.
The HALT pin is important to the RESET line's existence (as we mentioned
above), in order to initialize things properly. This pin has still more
functions: when the pin is low while RESET is high, the processor goes
into a halt state. This state causes the DMA pin to set the processor into the
tri-state condition. The HALT condition ends when HALT is high again.
This signal can be used in the design of single-step control.
HALT is also bi-directional. When the processor signals this line to become
low, it means that a major error has occurred (e.g., doubled bus and
address errors).
A low state on the BERR pin will call up exception handling, which runs
basically like an external interrupt. In an orderly system, every access to the
asynchronous bus quits with the DTACK signal. When DTACK is
outputting, however, the hardware can produce a BERR, which informs the
processor of any errors found. A further use for BERR is in connection
with the MMU, to test for proper memory access of a specific range; this
access is signaled by the FC pins. If protected memory is tried for in user
mode, a BERR will turn up.
When both BERR and HALT are low, the processor will "re-execute" the
instruction at which it stopped. If it doesn't run properly on the second
"go-round", then it's called a doubled bus error, and the processor halts.
The eighth group of connections are for voltage and ground.
12
Abacus Software
Atari ST Internals
1.2 The Custom Chips
The Atari ST has four specially developed ICs. These chips (GLUE,
MMU, DMA and SHIFTER) play a major role in the low price of the ST,
since each chip performs several hundred overlapping functions. The first
prototype of the ST was 5 X 50 X 30 cm. in size, mostly to handle all those
TTL ICs. Once multiple functions could be crammed into four ICs, the ST
became a saleable item. Then again, the present ST hasn't quite reached the
ultimate goal — it still has eight TTLs.
Naturally, since these chips were specifically designed by Atari for the ST,
they haven't been publishing any spec sheets. Even without any data specs,
we can give you quite a bit of information on the workings of the ICs.
An interesting fact about these ICs is that they're designed to work in
concert with one another. For example, the DMA chip can't operate alone.
It hasn't an address counter, and is incapable of addressing memory on its
own (functions which are taken care of by the MMU). It's the same with
SHIFTER - it controls video screen and color, but it can't address video
RAM. Again, MMU handles the addressing.
The system programmer can easily figure out which IC has which register.
It is only essential to be able to recognize the address of the register, and
how to control it. We’re going to spend some time in this chapter exploring
the pins of the individual ICs.
The most important IC of the "foursome" is GLUE. Its title speaks for the
function - a glue or paste. This IC, with its 68 pins, literally holds the
entire system together, including decoding the address range and working
the peripheral ICs.
Furthermore, the DMA handshake signals BR, BG and BGACK are
produced/output by GLUE. The time point for DMA request is dictated by
GLUE by the signal from the DMA controller. GLUE also has a BG (Bus
Grant) input, as well as a BGO (Bus Grant Out).
The interrupt signal is produced by GLUE; in the ST, only IPL1 and IPL2
are used for this. Without other hardware, you can't use NMI (interrupt
level 7). The pins MFPINT and IACK are used for interrupt control.
13
Abacus Software
Atari ST Internals
BGI*
RDY
VPA*
BERR*
DTACK*
IPL 1*
IPL 2*
8 MHZ in
GND
BLANK*
HSYNC
VSYNC
DE
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BGACK*
6850CS*
500HZ out
Figure 1.2-1 GLUE
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66
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64
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A21
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A17
A16
A15
A14
Vcc
A13
A12
All
A10
A9
A8
A7
A6
14
Abacus Software
Atari ST Internals
The function code pins are guided by GLUE, where memory access tasks
are performed (range testing and access authorization). Needless to say, the
BERR signal is also handled by this chip. VPA is particularly important to
the peripheral ICs and the appropriate select signals.
GLUE generates a timing frequency of 8 mHz. Frequencies between 2
mHz (sound chip's operating frequency) and 500 kHz (timing for keyboard
and MIDI interface) can be produced.
HSYNC, VSYNC, BLANK and DE (Display Enable) are generated by
GLUE for monitor operation. The synchronous timing can be switched on
and off, and external sync-signals sent to the monitor. This will allow you
to synchronize the ST's screen with a video camera.
The MMU also has a total of 68 pins. This IC performs three vital tasks.
The most important task is coupling the multiplexed address bus of dynamic
RAM with the processor's bus (handled by address lines A1 to A21). This
gives us an address range totaling 4 megabytes. Dynamic RAM is
controlled by RASO, RAS1, CASOL, CASOH, CAS1L and CAS1H, as
well as the multiplexed address bus on the MMU. DTACK, R/W, AS, LDS
and UDS are also controlled by MMU.
We've already mentioned another important function of the MMU: it works
with the SHIFTER to produce the video signal (the screen information is
addressed in RAM, and SHIFTER conveys the information). Counters are
incorporated in the MMU for this; a starting value is loaded, and within 500
nanoseconds, a word is addressed in memory and the information is sent
over DCYC. The starting value of the video counter (and the screen
memory position) can be shifted in 25 6- byte increments.
Another integrated counter in MMU, as mentioned earlier, is for addressing
memory using the DMA. This counter begins with every DMA access (disk
or hard disk), loading the address of the data being transferred. Every
transfer automatically increments the counter.
The SHIFTER converts the information in video RAM into impulses
readable on a monitor. Whether the ST is in 640 X 200 or 320 X 200
resolution, SHIFTER is involved.
15
Abacus Software
Atari ST Internals
Figure 1.2-2 MMU
*
CO
Q
D
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27
CMPCS
28
DCYC*
29
RDAT*
30
DEV*
31
AS
32
RAM*
33
R/W*
34
A15
35
A14
36
A13
37
A12
38
All
39
A10
40
A9
41
A8
42
A7
43
D
9
LATCH
D
8
RASO
D
7
CASOLOW
D
6
CASOHIGH
D
5
16MHZ IN
D
4
D7
D
3
D6
D
2
D5
m
1
D4
D
68
D3
D
67
D2
D
66
D1
D
65
DO
D
64
MAD 9
D
63
MAD 8
D
62
MAD 7
D
61
GND
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16
Abacus Software
Atari ST Internals
The information from RAM is transferred to SHIFTER on the signal
LOAD. A resolution of 640 X 400 points sends the video signal over the
MONO connector. Since color is impossible in that mode, the RGB
connection is rendered inactive. The other two resolutions set MONO
output to inactive, since all screen information is being sent out the RGB
connection in those cases.
The third color connection works together with external equipment as a
digital/analog converter. Individual colors are sent out over different pins,
to give us color on our monitor. Pins Rl- R5 on the address bus make up
the "palette registers". These registers contain the color values, which are
placed in individual bit patterns. The 16 palette registers hold a total of 16
colors for 320 X 200 mode. Note, however, that since these are based on
the "primary" colors red, green and blue, these colors can be adjusted in 8
steps of brightness, bringing the color total to 5 12.
The DMA controller is like SHIFTER, only in a 40-pin housing; it is used
to oversee the floppy disk controller, the hard disk, and any other
peripherals that are likely to appear.
The speed of data transfer using the floppy disk drive offers no problems to
the processor. It's different with hard disks; data moves at such high speed
that the 68000 has to send a "pause" over the 8 mHz frequency. This pace
is made possible by the DMA.
The DMA is joined to the processor's data bus to help transfer data. Two
registers within the machine act as a bi-directional buffer for data through
the DMA port; we’ll discuss these registers later. One interesting point:
The processor's 16-bit data bus is reduced to 8 bits for floppy/hard disk
work. Data transfer automatically transfers two bytes per word.
The signals CA1, CA2, CRAY, FDCS and FDRQ manage the floppy disk
controller. CA1 and CA2 are signals which the floppy disk controller
(FDC) uses to select registers. CR/W determine the direction of data
transfer from/to the FDC, and other peripherals connected to the DMA port.
The RDY signal communicated with GLUE (DMA-request) and MMU
(address counter). This signal tells the DMA to transfer a word.
As you can see, these ICs work in close harmony with one another, and
each would be almost useless on its own.
18
Abacus Software
Atari ST Internals
Figure 1.2-4 DMA
V c c
CLK
R D Y
ACK*
C D 0
C D 1
CD 2
CD 3
CD 4
CD 5
CD 6
CD 7
G N D
C A 2
C A 1
CR/W*
HDCS *
HD RQ
FD C S *
FDRQ
19
Abacus Software
Atari ST Internals
1.3 The WD 1772 Floppy Disk Controller
Although the 1772 from Western Digital has only 28 pins, this chip contains
a complete floppy disk controller (FDC) with capabilities matching 40-pin
controllers. This IC is software-compatible with the 1790/2790 series.
Here are some of the 1772's features:
Simple 5-volt current
Built-in data separator
Built-in copy compensation logic
Single and double density
Built-in motor controls
Although the user has his/her choice of disk format, e.g. sector length,
number of sectors per track and number of tracks per diskette, the "normal"
format is the optimum one for data transfer. So, Apple or Commodore
diskettes can't be used.
Before going on to details of the FDC, let's take a moment to look at the 28
pins of this IC.
1.3.1 1772 Pins
These pins can be placed in three categories. The first group consists of the
power connections.
Vcc:
+5 volts current.
GND:
Ground connection.
MR:
Master reset. FDC reinitializes when this is low.
The second set are processor interface pins. These pins carry data between
the processor and the FDC.
20
Abacus Software
Atari ST Internals
Figure 1.3-1 FDC 1772
INTR
DRQ
D D *
HP*
INDEX
TRK 0
W D
W G
M 0
RD *
C LK
D I RC
STEP
Vcc
21
Abacus Software
Atari ST Internals
D0-D7:
Eight-bit bi-directional bus; data, commands and status
information go between FDC and system.
CS:
FDC can only access registers when this line is low.
R/W:
Read/Write. This pin states data direction. HIGH= read by FDC,
LOW= write from FDC.
A0,A1:
These bits determine which register is accessed (in conjunction
with R/W). The 1772 has a total of five registers which can both
read and write to some degree. Other registers can only read OR
write. Here is a table to show how the manufacturer designed
them:
A1
0
0
1
1
A Q _ R/W=l
0 Status Reg.
1 Track Reg.
0 Sector Reg.
1 Data Reg.
R/W=0
Command Reg .
Track Reg.
Sector Reg.
Data Reg.
DRQ:
Data Request. When this output is high, either the data register is
full (from reading), and must be "dumped", or the data register is
empty (writing), and can be refilled. This connection aids the
DMA operation of the FDC.
CLK:
Clock. The clock signal counts only to the processor bus. An
input frequency of 8 mHz must be on, for the FDC's internal
timing to work.
The third group of signals make up the floppy interface.
STEP:
Sends an impulse for every step of the head motor.
DIRC:
Direction. This connection decides the direction of the head; high
moves the head towards center of the diskette.
22
Abacus Software
Atari ST Internals
RD:
Read Data. Reads data from the diskette. This information
contains both timing and data impulses — it is sent to the internal
data separator for division.
MO:
Motor On. Controls the disk drive motor, which is automatically
started during read/write/whatever operations.
WG:
Write Gate. WG will be low before writing to diskette. Write
logic would be impossible without this line.
WD:
Write Data. Sends serial data flow as data and timing impulses.
TROO:
Track 00. This moves read/write head to track 00. TROO would
be low in this case.
IP:
Index Pulse. The index pulses mark the physical beginnings of
every track on a diskette. When formatting a disk, the FDC
marks the start of each track before formatting the disk.
WPRT:
Write Protect. If the diskette is write-protected, this input will
react.
DDEN:
Double Density Enable. This signal is confined to floppy disk
control; it allows you to switch between single-density and
double-density formats.
23
Abacus Software
Atari ST Internals
1.3.2 1772 Registers
CR (Command Register):
Commands are written in this 8-bit register. Commands should
only be written in CR when no other command is under
execution. Although the FDC only understands 11 commands,
we actually have a large number of possibilities for these
commands (we'll talk about those later).
STR (Status Register):
Gives different conditions of the FDC, coded into individual bits.
Command writing depends on the meaning of each bit. The
status register can only be read.
TR (Track Register):
Contains the current position of the read/write head. Every
movement of the head raises or lowers the value of TR
appropriately. Some commands will read the contents of TR,
along with information read from the disk. The result affects the
Status Register. TR can be read/written.
SR (Sector Register):
SR contains the number of sectors desired from read/write
operations. Like TR, it can be used for either operation.
DR (Data Register):
DR is used for writing data to/ reading data from diskette.
24
Abacus Software
Atari ST Internals
1.3.3 Programming the FDC
Programming this chip is no big deal for a system programmer. Direct (and
in most cases, unnecessary) programming is made somewhat harder AND
drastically simpler by the DMA chip. The 1 1 FDC commands are divided
into four types.
Type Function
1 Restore, look for track 00
1 Seek, look for a track
1 Step, a track in previous direction
1 Step In, move head one track in (toward disk hub)
1 Step Out, move head one track out (toward edge of disk)
2 Read Sector
2 Write Sector
3 Read Address, read ID
3 Read Track, read entire track
3 Write Track, write entire track (format)
4 Force Interrupt
Type 1 Commands
These commands position the read/write head. The bit patterns of these five
commands look like this:
BIT
7
6
5
4
3
2
1
0
Restore
0
0
0
0
H
V
Rl
R0
Seek
0
0
0
1
H
V
Rl
R0
Step
0
0
1
U
H
V
Rl
R0
Step In
0
1
0
u
H
V
Rl
R0
Step Out
0
1
1
u
H
V
Rl
R0
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Abacus Software
Atari ST Internals
All five commands have several variable bits; bits RO and R1 give the time
between two step impulses. The possible combinations are:
R1 RO STEP RATE
0 02 milliseconds
0 13 milliseconds
1 05 milliseconds
1 16 milliseconds
These bits must be set by the command bytes to the disk drive. The V-bit is
the so-called "verify flag". When set, the drive performs an automatic
verify after every head movement. The H-bit contains the spin-up
sequence. The system delays disk access until the disk motor has reached
300 rpm. If the H-bit is cleared, the FDC checks for activation of the
motor-on pins. When the motor is off, this pin will be set high (motor on),
and the FDC waits for 6 index impulses before executing the command. If
the motor is already running, then there will be no waiting time.
The three different step commands have bit 4 designated a U- bit. Every
step and change of the head appears here.
Type 2 Commands
These commands deal with reading and writing sectors. They also have
individual bits with special meanings.
BIT 7 6 5 4 3
2
1
0
Read Sector 1 0 0 M H
E
0
0
Write Sector 1 0 1 M H
E
P
A0
The H-bit is the previously described start-up bit. When the E-bit is set, the
FDC waits 30 milliseconds before starting the command. This delay is
important for some disk drives, since it takes time for the head to change
tracks. When the E-bit reads null, the command will run immediately.
The M-bit determines whether one or several sectors are read one after
another. On a null reading, only one sector will be read from/written to.
Multi-sector reading sets the bit, and the FDC increments the counter at each
new sector read.
Bits 0 and 1 must be cleared for sector reading. Writing has its own special
meaning: the A0 bit conveys to bit 0 whether a cleared or normal data
26
Abacus Software
Atari ST Internals
address mark is to be written. Most operating systems don't use this option
(a normal data address mark is written).
The P-bit (bit 1) dictates whether pre-compensation for writing data is
turned on or off. Pre-compensation is normally set on; it supplies a higher
degree of protection to the inner tracks of a diskette.
Type 3 Commands
Read Address gives program information about the next ED field on the
diskette. This ID field describes track, sector, disk side and sector length.
Read Track gives all bytes written to a formatted diskette, and the data
"between sectors". Write Track formats a track for data storage. Here are
the bit patterns for these commands:
BIT
Read Address
Read Track
Write Track
76543210
1100HE00
1110HE00
1111HEP0
The H- and E-bits also belong to the Type 2 command set (spin-up and
head-settle time). The P-bit has the same function as in writing sectors.
Type 4 Commands
There's only one command in this set: Force Interrupt. This command can
work with individual bits during another FDC command. When this
command comes into play, whatever command was currently running is
ended.
BIT 76543210
Force Interrupt 1 1 0 1 13 12 II 10
Bits 10-13 present the conditions under which the interrupt is pressed. 10
and II have no meaning to the 1772, and remain low. If 12 is set, an
interrupt will be produced with every index impulse. This allows for
software controlled disk rotation. If 13 is set, an interrupt is forced
immediately, and the currently-running command ends. When all bits are
null, the command ends without interruption.
27
Abacus Software
Atari ST Internals
1.4 The MFP 68901
MFP is the abbreviation for Multi-Function Peripheral. This name is no
exaggeration; wait until you see what it can do! Here's a brief list of the
most noteworthy features:
8 -bit parallel port
Data direction of every port bit is individually programmable
Port bits usable as interrupt input
16 possible interrupt sources
Four universal timers
Built-in serial interface
1.4.1 The 68901 Connections
The 48 pins of the MFP are set apart in function groups. The first function
group is the power connection set:
GND, Vcc, CLK:
Vcc and GND carry voltage to and from the MFP. CLK is the
clock input; this clock signal must not interfere with the system
timer of the processor. The ST's MFP operates at a frequency of
4 mHz.
Communication with the data bus of the processor is maintained with
D0-D7, DTACK, RS 1-RS5 and RESET.
D0-D7:
These bi-directional pins normally work with the 8 lowest data
bits of the 68000. It is also possible to connect with D8 through
D15, but it's impossible to produce non-auto interrupts. Thus,
interrupt vectors travel along the low order 8 data bits.
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Abacus Software
Atari ST Internals
Figure 1.4-1 MFP 68901
c s *
D S *
D TACK *
I ACK*
D 7
D 6
D 5
D 4
D 3
D 2
D 1
D 0
V s S
C L K
X E I *
X E O *
INTR*
R R *
T R *
I 7
I 6
I 5
X 4
13
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Abacus Software
Atari ST Internals
CS (Chip Select):
This line is necessary to communication with the MFP. CS is
active when low.
DS (Data Strobe):
This pin works with either LDS or UDS on the processor.
Depending on the signal, MFP will operate either the lower or
upper half of the data bus.
DTACK (Data Transfer ACKnoledge):
This signal shows the status of the bus cycle of the processor
(read or write).
RS1-RS5 (Register Select):
These pins normally connect with to the bottom five address lines
of the processor, and serve to choose from the 24 internal
registers.
RESET:
If this pin is low for at least 2 microseconds, the MFP initializes.
This occurs on power-up and a system reset.
The next group of signals cover interrupt connections (IRQ, IACK, IEI and
IEO).
IRQ (Interrupt ReQuest):
IRQ will be low when an interrupt is triggered in the MFP. This
informs the processor of interrupts.
IACK (Interrupt ACKnowledge):
On an interrupt (IRQ and IEI), the MFP sends a low signal over
IACK and DS on the data lines. Since 16 different interrupt
sources are available, this makes handling interrupts much
simpler.
IEI, IEO (Interrupt Enable In/ Out):
These two lines permit daisy-chaining of several MFPs, and
determine MFP priority by their positioning in this chain. IEI
would work through the MFP with the highest priority. IEO of
the second MFP would remain unswitched. On an interrupt, a
signal is sent over IACK, and the first MFP in the chain will
acknowledge with a high IEO.
30
Abacus Software
Atari ST Internals
Next, we'll look at the eight I/O lines.
100-7 (Input/Output):
These pins use one or all normal I/O lines. The data direction of
each port bit is set up in a data direction register of its own. In
addition, though, every port bit can be programmed to be an
interrupt input.
The timer pins make up yet another group of connections:
XTAL1,2 (Timer Clock Crystal):
A quartz crystal can be connected to these lines to deliver a
working frequency for the four timers.
TAI,TBI (Timer Input):
Timers A and B can not only be used as real counters differently
from timers C and D with the frequency from XTAL1 and 2, but
can also be set up for event counting and impulse width
measurement. In both these cases, an external signal (Timer
Input) must be used.
TAO,TBO,TCO,TDO (Timer Output):
Every timer can send out its status on each peg (from 01 to 00).
Each impulse is equal to 01.
The second-to-last set of signals are the connections to the universal serial
interface. The built-in full duplex of the MFP can be run synchronously or
asynchronously, and in different sending and receiving baud rates.
SI (Serial Input):
An incoming bit current will go up the SI input.
SO (Serial Output):
Outgoing bit voltage (reverse of SI).
RC (Receiver Clock):
Transfer speed of incoming data is determined by the frequency
of this input; the source of this signal can, for example, be one of
the four timers.
TC (Transmitter Clock):
Similar to RC, but for adjusting the baud-rate of data being
transmitted.
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Abacus Software
Atari ST Internals
The final group of signals aren't used in the Atari ST. They are necessary
when the serial interface is operated by the DMA.
RR (Receiver Ready):
This pin gives the status of the receiving data registers. If a
character is completely received, this pin sends current.
TR (Transmitter Ready):
This line performs a similar function for the sender section of the
serial interface. Low tells the DMA controller that a new
character in the MFP must be sent.
1.4.2 The MFP Registers
As we've already mentioned, the 68901 has a total of 24 different registers.
This large number, together with the logical arrangement, makes
programming the MFP much easier.
Reg 1 GPIP, General Purpose I/O Interrupt Port
This is the data register for the 8-bit ports, where data from the
port bits is sent and read.
Reg 2 AER, Active Edge Register
When port bits are used for input, this register dictates whether
the interrupt will be a low-high- or high-low conversion. Zero is
used in the high-low change, one for low-high.
Reg 3 DDR, Data Direction Register
We've already said that the data direction of individual port bits
can be fixed by the user. When a DDR bit equals 0, the
corresponding pin becomes an input, and 1 makes it an output.
Port bit positions are influenced by AER and DDR bits.
32
Abacus Software
Atari ST Internals
Reg 4,5 IERA,IERB, Interrupt Enable Register
Every interrupt source of the MFP can be separately switched on
and off. With a total of 16 sources, two 8-bit registers are
needed to control them. If a 1 has been written to IERA or
IERB, the corresponding channel is enabled (turned on).
Conversely, a zero disables the channel. If it comes upon a
closed channel caused by an interrupt, the MFP will completely
ignore it. The following table shows which bit is coordinated
with which interrupt occurrence:
IERA
Bit 7:
Bit 6:
Bit 5 :
Bit 4:
Bit 3:
Bit 2:
Bit 1:
Bit 0:
I/O port bit 7 (highest priority)
I/O port bit 6
Timer A
Receive buffer full
Receive error
Sender buffer empty
Sender error
Timer B
IERB
Bit 7:
Bit 6:
Bit 5 :
Bit 4 :
Bit 3:
Bit 2 :
Bit 1:
Bit 0:
I/O
port
bit
5
I/O
port
bit
4
Timer C
Timer D
I/O
port
bit
3
I/O
port
bit
2
I/O
port
bit
1
I/O
port
bit
0,
lowest priority
This arrangement applies to the IP-, IM- and IS-registers
discussed below.
Reg 6,7 IPRA,IPRB, Interrupt Pending Register
When an interrupt occurs on an open channel, the appropriate bit
in the Interrupt Pending Register is set to 1. When working with
a system that allows vector creation, this bit will be cleared when
the MFP puts the vector number on the data bus. If this isn't
possible, die IPR must be cleared using software. To clear a bit,
a byte in the MFP will show the location of the specific bit.
The bit arrangement of the IPR bit arrangement is shown in the
table for registers 4 and 5 (see above).
33
Abacus Software
Atari ST Internals
Reg 8,9 ISRA,ISRB, Interrupt In-Service Register
The function of these registers is somewhat complicated, and
depends upon bit 3 of register 12. This bit is an S-bit, which
determines whether the 68901 is working in "Software End-of-
Interrupt" mode (SEI) or in "Automatic End-of-Interrupt" mode
(AEI). AEI mode clears the IPR (Interrupt Pending Bit), when
the processor gets the vector number from the MFP during an
LACK cycle. The appropriate In-Service bit is cleared at the same
time. Now a new interrupt can occur, even when the previous
interrupt hasn't finished its work.
SEI mode sets the corresponding ISR-bit when the vector
number of the interrupt is requested by the processor. At the
interrupt routine's end, the bit designated within the MFP must
be cleared. As long as the Interrupt In-Service bit is set, all
interrupts of lower priority are masked out by the MFP. Once the
Pending-bit of the active channel is cleared, the same sort of
interrupt can occur a second time, and interrupts of lesser priority
can occur as well.
Reg 10,11 IMRA,IMRB Interrupt Mask Register
Individual interrupt sources switched on by IER can be masked
with the help of this register. That means that the interrupt is
recognized from within and is signaled in the IPR, even if the
IRQ line remains high.
Reg 12 VR Vector Register
In the cases of interrupts, the 68901 can generate a vector number
corresponding to the interrupt source requested by the processor
during an Interrupt Acknowledge Cycle. All 16 interrupt
channels have their own vectors, with their priorities coded into
the bottom four bits of the vector number (the upper four bits of
the vector are copied from the vector register). These bits must
be set into VR, therefore.
Bit 3 of VR is the previously mentioned S-bit. If this bit is set
(like in the ST), then the MFP operates in "Software End-of-
Interrupt" mode; a cleared bit puts the system into "Automatic
End-of-Interrupt" mode.
34
Abacus Software
Atari ST Internals
Reg 13,14 TACR,TBCR Timer A/B Control Register
Before proceeding with these registers, we should talk for a
moment about the timer. Timers A and B are both identical.
Every timer consists of a data register, a programmable feature
and an 8-bit count-down counter. Contents of the counters will
decrease by one every impulse. When the counter stands at 01,
the next impulse changes die corresponding timer to the output of
its pins. At the same time, the value of the timer data register is
loaded into the timer. If this channel is set by the IER bit, the
interrupt will be requested. The source of the timer beats will
usually be those quartz frequencies from XTAL1 and 2. This
operating mode is called delay mode, and is available to timers C
and D.
Timers A and B can also be fed external impulses using timer
inputs TAI and TBI (in event count mode). The maximum
frequency on timer inputs should not surpass 1/4 of the MFP's
operating frequency (that is, 1 mHz).
Another peculiarity of this operating mode is the fact that the
timer inputs for the interrupts are I/O pins 13 and 14. By
programming the corresponding bits in the AER, a pin-jump can
be used by the timer inputs to request an interrupt. TAI is joined
with pin 13, TBI by pin 14. Pins 13 and 14 can also be used as
I/O lines without interrupt capability.
Timers A and B have yet a third operating mode (pulse-length
measurement). This is similar to Delay Mode, with the difference
that the timer can be turned on and off with TAI and TBI. Also,
when pins 13 and 14 are used, the AER-bits can determine
whether the timer inputs are high or low. If, say, AER-bit 4 is
set, the counter works when TAI is high. When TAI changes to
low, an interrupt is created.
Now we come to TACR and TBCR. Both registers only use the
fifth through eighth bits. Bits 0 to 3 determine the operating
mode of each timer:
35
Abacus Software
Atari ST Internals
BIT 3210
Function
0000 Timer stop, no function executed
0001 Delay mode, subdivider divides by 4
0010 Delay mode, subdivider divides by 10
0011 Delay mode, subdivider divides by 16
0011 Delay mode, subdivider divides by 16
0100 Delay mode, subdivider divides by 50
0101 Delay mode, subdivider divides by 64
0110 Delay mode, subdivider divides by 100
0111 Delay mode, subdivider divides by 200
1000 Event Count Mode
1
0
0
1
Pulse
extension
mode, subdivider
divides
by
4
1
0
1
0
Pulse
extension
mode, subdivider
divides
by
10
1
0
1
1
Pulse
extension
mode, subdivider
divides
by
16
1
1
0
0
Pulse
extension
mode, subdivider
divides
by
50
1
1
0
1
Pulse
extension
mode, subdivider
divides
by
64
1
1
1
0
Pulse
extension
mode, subdivider
divides
by
100
1
1
1
1
Pulse
extension
mode, subdivider
divides
by
200
Bit 4 of the Timer Control Register has a particular function.
This bit can produce a low reading for the timer being used with
it at any time. However, it will immediately go high when the
timer runs.
Reg 15 TCDCR Timers C and D Control Register
Timers C and D are available only in delay mode; thus, one byte
controls both timers. The control information is programmed
into the lower three bits of the nibbles (four- bit halves). Bits 0
and 2 arrange Timer D, Timer C is influenced by bits 4 and 6.
Bits 3 and 7 in this register have no function.
2
1
0
Function - Timer D
6
5
4
Function - Timer C
0
0
0
Timer
Stop
0
0
1
Delay
Mode, division
by
4
0
1
0
Delay
Mode, division
by
10
0
1
1
Delay
Mode, division
by
16
1
0
0
Delay
Mode, division
by
50
1
0
1
Delay
Mode, division
by
64
1
1
0
Delay
Mode, division
by
100
1
1
1
Delay
Mode, division
by
200
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Atari ST Internals
Reg 16-19 TADR,TBDR,TCDR,TDDR Timer Data Registers
The four Timer Data Registers are loaded with a value from the
counter. When a condition of 01 is reached, an impulse occurs.
A continuous countdown will stem from this value.
Reg 20 SCR Synchronous Character Register
A value will be written to this register by synchronous data
transfer, so that the receiver of the data will be alerted. When
synchronous mode is chosen, all characters received will be
stored in the SCR, after first being put into the receive buffer.
Reg 21 UCR,USART Control Register
USART is short for Universal Synchronous/Asynchronous
Receiver/Transmitter. The UCR allows you to set all the
operating parameters for the interfaces. Parameters can also be
coded in with the timers.
Bit 0 : unused
Bit 1 : 0=Odd parity
l=Even parity
Bit 2 : 0=No parity (bit 1 is ignored)
l=Parity according to bit 1
Bits 3,4 : These bis control the number of
start- and stopbits and the
format desired.
Bit 4 3 Start Stop Format
000 0 Synchronous
011 1 Asynchronous
10 1 1,5 Asynchronous
111 2 Asynchronous
Bits 5,6 : These bits give the
"wordlength" of the data bits
to be transferred.
Bits 6 5 Word length
008 bits
017 bits
106 bits
115 bits
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Bit 7 : 0=Frequency from TC and RC
directly used as transfer
frequency (used only for
synchronous transfer)
l=Frequency in TC and RC
internally divided by 16.
Reg 22 RSR Receiver Status Register
The RSR gives information concerning the conditions of all
receivers. Again, the different conditions are coded into
individual bits.
Bit 0 Receiver Enable Bit
When this bit is cleared, receipt is immediately turned off.
All flags in RSR are automatically cleared. A set bit means
that the receiver is behaving normally.
Bit 1 Synchronous Strip Enable
This bit allows synchronous data transfer to determine
whether or not a character in the SCR is identical to a
character in the receive buffer.
Bit 2 Match/Character in Progress
When in synchronous transfer format, this bit signals that a
character identical with the SCR byte would be received.
In asynchronous mode, this bit is set as soon as the startbit
is recognized. A stopbit automatically clears this bit.
Bit 3 Found - Search/Break Detected
This bit is set in synchronous transfer format, when a
character received coincides with one stored in the SCR.
This condition can be treated as an interrupt over the
receiver's error channel. Asynchronous mode will cause
the bit to set when a BREAK is received. The break
condition is fulfilled when only zeroes are received
following a startbit. To distinguish between a BREAK
from a "real" null, this line should be low.
Bit 4 Frame Error
A frame error occurs when a byte received is not a null, but
the stopbit of the byte IS a null.
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Bit 5 Parity Error
The condition of this bit gives information as to whether
parity on the last received character was correct. If the
parity test is off, the PE bit is untouched.
Bit 6 Overrun Error
This bit will be set when a complete character is in the
receiver floating range but not read into the receive buffer.
This error can be operated as an interrupt.
Bit 7 Buffer Full
This bit is set when a character is transferred from the
floating register to the receive buffer. As soon as the
processor reads the byte, the bit is cleared.
Reg 23 TSR Transmitter Status Register
Whereas the RSR sends receiver information, the TSR handles
transmission information.
Bit 0 Transmitter Enable
The sending section is completely shut off when this bit is
cleared. At the same time the End-bit is cleared and the UE-
bit is set (see below). The output to the receiver is set in
the corresponding H- and L-bits.
Bits 1,2 High- and Low-bit
These bits let the programmer decide which mode of output
the switched-off transmitter will take on. If both bits are
cleared, the output is high. High-bit only will create high
output; low-bit, low output. Both bits on will switch on
loop-back-mode. This state loops the output from the
transmitter with receiver input. The output itself is on the
high-pin.
Bit 3 Break
The break-bit has no function in synchronous data transfer.
In asynchronous mode, though, a break condition is sent
when the bit is set.
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Bit 4 End of Transmission
If the sender is switched off during running transmission,
the end-bit will be set as soon as the current character has
been sent in its entirety. When no character is sent, the bit
is immediately set.
Bit 5 Auto Turnaround
When this bit is set, the receiver is automatically switched
on when the transmitter is off, and a character will
eventually be sent.
Bit 6 Underrun Error
This bit is switched on when a character in the sender
floating register will be sent, before a new character is
written into the send buffer.
Bit 7 Buffer Empty
This bit will be set when a character from the send buffer
will be transferred to the floating register. The bit is
cleared when new data is written to the send buffer.
Reg 24 UDR, USART Data Register
Send/receive data is sent over this register. Writing sends data in
the send buffer, reading gives you the contents of the receive
buffer.
Abacus Software
Atari ST Internals
1.5 The 6850 ACIAs
ACIA is short for "Asynchronous Communications Interface Adapter".
This 24-pin IC has all the components necessary for operating a serial
interface, as well as error-recognizing and data-formatting capabilities.
Originally for 6800-based computers, this chip can be easily tailored for
6502 and 68000 systems. The ST has two of these chips. One of them
communicates with the keyboard, mouse, joystick ports, and runs the
clock. Keyboard data travels over a serial interface to the 68000 chip. The
second ACIA is used for operating the MIDI interface.
Parameter changes in the keyboard ACIA are not recommended: The
connection between keyboard and ST can be easily disrupted. The MIDI
interface is another story, though — we can create all sorts of practical
applications. Incidentally, nowhere else has it been mentioned that the
MIDI connections can be used for other purposes. One idea would be to
use the MIDI interfaces of several STs to link them together (for schools or
offices, for example).
1.5.1 The Pins of the 6850
For those of you readers who aren't very well-acquainted with the
principles of serial data transfer, we've included some fairly detailed
descriptions in the pin layout which follows.
Vss
This connection is the "ground wire" of the IC.
RX DATA Receive Data
This pin receives data; a start-bit must precede the least significant
data-bit before receipt.
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RX CLK Receive Clock
This pin signal determines baud-rate (speed at which the data is
received), and is synchronize to the incoming data. The
frequency of RX CLK is patterned after the desired transfer
speed and after the internally programmed division rate.
TX CLK Transmitter Clock
Like RX CLK, only used for transmission speed.
RTS Request To Send .
This output signals the processor whether the 6850 is low or
high; mostly used for controlling data transfer. A low output
will, for example, signal a modem that the computer is ready to
transmit.
TX DATA Transmitter Data
This pin sends data bit-wise (serially) from the computer.
IRQ Interrupt Request
Different circumstances set this pin low, signaling the 68000
processor. Possible conditions include completed transmission
or receipt of a character.
CS 0,1,2 Chip Select rT,i , . ,
These three lines are needed for ACIA selection. The relatively
high number of CS signals help minimize the amount of
hardware needed for address decoding, particularly in smaller
computer systems.
RS Register Select
This signal communicates with internal registers, and works
closely with the R/W signal. We shall talk about these registers
later.
Vcc Voltage ,
This pin is required of all ICs - this pin gets an operating voltage
of 5V.
R/W Read/Write ,
This tells the processor the "direction” of data traveling through
the ACIA. A high signal tells the processor to read data, and low
writes data in the 6850.
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E Enable
The E-signal determines the time of reading/writing. All
read/write processes with this signal must be synchronous.
DO - D7 Data
These data lines are connected to those of the 68000. Until the
ACIA is accessed, these bidirectional lines are all high.
DCD Data Carrier Detect
A modem control signal, which detects incoming data. When
DCD is high, serial data cannot be received.
CTS Clear To Send
CTS answers the computer on the signal RTS. Data transmission
is possible only when this pin is low.
1.5.2 The Registers of the 6850
The 6850 has four different registers. Two of these are read only. Two of
them are write only. These registers are distinguished by R/W and RS,
after the table below:
- Register _ ap.cpss
0 0 Control Register write
0 1 Sender Register write
1 0 Status Register read
1 1 Receive Register read
The sender/receiver registers (also known as the RX- and TX- buffers) are
for data transfer. When receiving is possible, the incoming bits are put in a
shift register. Once the specified number of bits has arrived, the contents of
the shift register are transferred to the TX buffer. The sender works in
much the same way, only in the reverse direction (RX buffer to sender shift
register).
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The Control Register
The eight-bit control register determines internal operations. To solve the
problem of controlling diverse functions with one byte, single bits are set up
as below:
CR 0,1 J
These bits determine by which factor the transmitter and receiver
clock will be divided. These bits also are joined with a master
reset function. The 6850 has no separate reset line, so it must be
accomplished through software.
CRl CRO
0 0 RXCLK/TXCLK without division
0 1 RXCLK/TXCLK by 16 (for MIDI)
1 0 RXCLK/TXCLK by 64 (for keyboard)
1 1 Master RESET
These so-called Word Select bits tell whether 7 or 8 data-bits are
involved; whether 1 or 2 stop-bits are transferred; and the type of
parity.
CR4
0
0
0
0
1
1
1
1
CR3 CR2
0 0
0 1
1 0
1 1
0 0
0 1
1 0
1 1
7 databits,
7 databits,
7 databits,
7 databits,
8 databits,
8 databits,
8 databits,
8 databits.
2 stopbits,
2 stopbits,
1 stopbit,
1 stopbit,
2 stopbit,
1 stopbit,
1 stopbit,
1 stopbit.
even parity
odd parity
even parity
odd parity
no parity
no parity
even parity
odd parity
These Transmitter Control bits set the RTS output pin, and allow
or prevent an interrupt through the ACIA when the send register
is emptied. Also, BREAK signals can be sent over the serial
output by this line. A BREAK signal is nothing more than a long
sequence of null bits.
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CR6
0
0
1
1
CR5
0 RTS low, transmitter IRQ disabled
1 RTS low, transmitter IRQ enabled
0 RTS high, transmitter IRQ disabled
1 RTS low, transmitter IRQ disabled, BREAK
sent
CR 7
The Receiver Interrupt Enable bit determines whether the receiver
interrupt will be on. An interrupt can be caused by the DCD line
changing from low to high, or by the receiver data buffer filling.
Besides that, an interrupt can occur from an OVERRUN (a
received character isn't properly read from the processor).
CR7
0 Interrupt disabled
1 Interrupt enabled
The Status Register
The Status Register gives information about the status of the chip. It also
has its information coded into individual bytes.
SRO
When this bit is high, the RX data register is full. The byte must
be read before a new character can be received (otherwise an
OVERRUN happens).
SRI
This bit reflects the status of the TX data buffer. An empty
register sets the bit.
SR2
A low-high change on pin DCD sets SR2. If the receiver
interrupt is allowable, the IRQ will be cancelled. The bit is
cleared when the status register and the receiver register are read.
This also cancels the IRQ. SR2 register remains high if the
signal on the DCD pin is still high; SR2 registers low if DCD
becomes low.
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SR3
This line shows the status of CTS. This signal cannot be altered
by a master reset, or by ACIA programming.
SR4
Shows "Frame errors". Frame errors are when no stop-bit is
recognized in receiver switching. It can be set with every new
character.
This bit displays the previously mentioned OVERRUN
condition. SR5 is reset when the RX buffer is read.
SR6
This bit recognizes whether the parity of a received character is
correct. The bit is set on an error.
This signals the state of the IRQ pins; this bit makes it possible to
switch several IRQ lines on one interrupt input. In cases where
an interrupt is program-generated, SR7 can tell which IC cut off
the interrupt.
The ACIAs in the ST
The ACIAs have lots of extras unnecessary to the ST. In fact, CTS, DCD
and RTS are not connected.
The keyboard ACIA lies at the addresses $FFFC00 and $FFFC02. Built-in
parameters are: 8-bit word, 1 stopbit, no parity, 7812.5 baud (500
kHz/64).
The parameters are the same for the MIDI chip, EXCEPT for the baud rate,
which runs at 31250 baud (500 kHz/16).
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1.6 The YM-2149 Sound Generator
The Yamaha YM-2149, a PSG (programmable sound generator) in the same
family as the General Instruments AY-3-8190, is a first-class sound
synthesis chip. It was developed to produce sound for arcade games. The
PSG also has remarkable capabilities for generating/altering sounds.
Additionally, the PSG can be easily controlled by joysticks, the computer
keyboard, or external keyboard switching. The PSG has two bidirectional
8-bit parallel ports. Here's some general data on the YM-2149:
• three independently programmable tone generators
• a programmable noise generator
• complete software-controlled analog output
• programmable mixer for tone/noise
• 15 logarithmically raised volume levels
• programmable envelopes (ASDR)
• two bidirectional 8-bit data ports
• TTL-compatible
• simple 5-volt power
The YM-2149 has a total of 16 registers. All sound capabilities are
controlled by these registers.
The PSG has several "functional blocks" each with its own job. The tone
generator block produces a square-wave sound by means of a time signal.
The noise generator block produces a frequency-modulated square-wave
signal, whose pulse- width simulates a noise generator. The mixer couples
the three tone generators’ output with the noise signal. The channels may
be coupled by programming.
The amplitude control block controls the output volume of the three
channels with the volume registers; or creates envelopes (Attack, Decay,
Sustain, Release, or ADSR), which controls the volume and alters the
sound quality.
The D/A converter translates the volume and envelope information into
digital form, for external use. Finally one function block controls the two
I/O ports.
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Abacus Software
Atari ST Internals
1.6.1 Sound Chip Pins
Vss:
This is the PSG ground connection.
NC.:
Not used.
ANALOG B:
This is the channel B output. Maximum output voltage is 1 vss.
ANALOG A:
Works like pin 3, but for channel A.
NC.:
Not used.
IOB7 - 0:
The IOB connections make up one of the two 8-bit ports on the
chip. These pins can be used for either input or output. Mixed
operation (input and output combined) is impossible within one
port, however both ports are independent of one another.
IOA7 - 0:
Like IOB, but for port A.
CLOCK:
All tone frequencies are divided by this signal. This signal
operates at a frequency between 1 and 2 mHz.
RESET:
A low signal from this pin resets all internal registers. Without a
reset, random numbers exist in all registers, the result being a
rather unmusical "racket".
A9:
This pin acts as a chip select-signal. When it is low, the PSG
registers are ready for communication.
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A8:
Similar to A9, only it is active when high.
TEST2:
Test2 is used for testing in the factory, and is unused in normal
operation.
BDIR & BC1,2:
The BDIR (Bus DIRection), BC1 and BC2 (Bus Control) pins
control the PSG’s register access.
BDIR BC2 BC1
0 0 0
0 0 1
0 10
Oil
10 0
10 1
110
111
PSG function
Inactive
Latch address
Inactive
Read from PSG
Latch address
Inactive
Write to PSG
Latch address
Only four of these combinations are of any use to us; those with a
5+ voltage running over BC2. So, here's what we have left:
BDIR BC1 Function
0 0 Inactive, PSG data bus high
0 1 Read PSG registers
1 0 Write PSG registers
1 1 Latch, write register number (
s)
DAO - 7:
These pins connect the sound chip to the processor, through the
data bus. The identifier DA means that both data and (register)
addresses can be sent over these lines.
ANALOG C:
Works with channel C (see ANALOG B, above).
TEST1:
See TEST2.
Ycc:
+5 volt pin.
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1.6.2 The 2149 Registers and their Functions
Now let's look at the functions of the individual registers. One point of
interest: the contents of the address register remain unaltered until
reprogrammed. You can use the same data over and over, without having
to send that data again.
Reg 0,1:
These register determine the period length, and the pitch of
ANALOG A. Not all 16 bits are used here; the eight bits of
register 0 (set frequency) and the four lowest bits of register 1
(control step size). The lower the 12-bit value in the register, the
higher the tone.
Reg 2,3:
Same as registers 0 and 1, only for channel B.
Reg 4,5:
Same as registers 0 and 1, only for channel C.
Reg 6:
The five lowest bits of this register control the noise generator.
Again, the smaller the value, the higher the noise "pitch".
Reg 7:
Bit
0 : Channel
A tone on/off
0=on
/ l=of f
Bit
1 : Channel
B tone on/off
0=on
/ 1— of f
Bit
2 : Channel
C tone on/off
0=on
/ l=of f
Bit
3 : Channel
A noise on/off
0=on
/ l=of f
Bit
4 : Channel
B noise on/off
0=on
/ l=of f
Bit
5 : Channel
C noise on/off
0=on
/ l=of f
Bit
6: Port A
in/ output
0=in
/ l=out
Bit
7 : Port B
in/ output
0=in
/l=out
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Abacus Software
Atari ST Internals
Figure 1.6-2 Envelopes of the PSG
REG 15
Abacus Software
Atari ST Internals
Reg 8:
Bits 0-3 of this register control the signal volume of channel A.
When bit 4 is set, the envelope register is being used and the
contents of bits 0-3 are ignored.
Reg 9:
Same as register 8, but for channel B.
Reg 10:
Same as register 8, but for channel C.
Reg 11,12:
The contents of register 1 1 are the low-byte and the contents of
register 12 are the high-byte of the sustain.
Reg 13:
Bits 0-3 determine the waveform of the envelope generator. The
possible envelopes are pictured in Figure 1.6-2.
Reg 14,15:
These registers comprise the two 8-bit ports. Register 14 is
connected to Port A and register 15 is connected to Port B. If
these ports are programmed as output (bits 7 and 8 of register 7)
then values may be sent through these registers.
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Abacus Software
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1.7 I/O Register Layout in the ST
The entire I/O range (all peripheral ICs and other registers) is controlled by a
32K address register - $FF8000 - $FFFFFF. Below is a complete table of
the different registers. CAUTION: The I/O section can be accessed only in
supervisor mode. Any access in user mode results in a bus-error.
$FF8000 Memory configuration
$FF8200 Video display register
$FF8400 Reserved
$FF8600 DMA/disk controller
$FF8800 Sound chip
$FFFA00 MFP 68901
$FFFC00 ACIAs for MIDI and keyboard
The addresses given refer only to the start of each register, and supply no
hint as to the size of each. More detailed information follows.
$FF8000 Memory Configuration
There is a single 8-bit register at $FF8001 in which the memory
configuration is set up (four lowest bits). The MMU-IC is designed for
maximum versatility within the ST. It lets you use three different types of
memory expansion chips: 64K, 256K, and the 1M chips. Since all of these
ICs are bit-oriented instead of byte-oriented, 16 memory chips of each type
are required for memory expansion. The identifier for 16 such chips
(regardless of memory capacity) is BANK. So, expansion is possible to
128 Kbyte, 512 Kbyte or even 2 Megabytes.
MMU can control two banks at once, using the RAS- and CAS- signals.
The table on the next page shows the possible combinations:
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Abacus Software
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SFF8001
Bit _ Memory configuration
3-0 Bank 0 Bank 1
0000
128K
0001
128K
0010
128K
0011
reserved
0100
512K
0101
512K
0100
512K
0100
reserved
1000
2M
1001
2M
1010
2M
1011
reserved
11XX
reserved
128K
512K
2 M
128K
512K
2 M, normally reserved
128K
512K
2M
The memory configuration can be read from or written to.
$ff§2QQ _ YifleQ Pisplay Register
This register is the storage area that determines the resolution and the color
palette of the video display.
$FF8201 8-bit Screen memory position (high-byte)
$FF8203 8-bit Screen memory position (low-byte)
These two read/write registers are located at the beginning of the 32K video
RAM.
In order to relocate video RAM, another register is used. This register is
three bytes long and is located at $FF8205. Video RAM can be relocated in
256-byte increments. Normally the starting address of video RAM is
$78000.
$FF8205
$FF8207
$FF820 9
8-bit
8-bit
8-bit
Video address
Video address
Video address
pointer
pointer
pointer
(high-byte)
(mid-byte)
(low-byte)
These three registers are read only. Every three microseconds, the contents
of these registers are incremented by 2.
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$FF820A BIT Synchronization mode
1 0
: 0=internal, l=external synchronization
: - 0=60 Hz , l=50Hz screen frequency
The bottom two bits of this register control synchronization mode; the
remaining bits are unused. If bit 0 is set, the HSync and VSync impulses
are shut off, which allows for screen synchronization from external sources
(monitor jack). This offers new realm of possibilities in video,
synchronization of your ST and a video camera, for example.
Bit 1 of the sync-mode register handles the screen frequency. This bit is
useful only in the two "lowest" resolutions. High-res operation puts the ST
at a 70 Hz screen frequency.
Sync mode can be read/written.
$FF8240 16-bit
$FF8242 16-bit
$FF825C 16-bit
$FF825E 16-bit
Color palette register 0
Color palette register 1
Color palette registers 2-13
Color palette register 14
Color palette register 15
Although the ST has a total of 512 colors, only 16 different colors can be
displayed on the screen at one time. The reason for this is that the user has
16 color pens on screen, and each can be one of 512 colors. The color
palette registers represent these pens. All 16 registers contain 9 bits which
affect the color:
FEDCBA987 654 3210
. XXX . XXX . XXX
The bits marked X control the registers. Bits 0-2 adjust the shade of blue
desired; 4-6, green hue; and 8- A, red. The higher the value in these three
bits, the more intense the resulting color.
Middle resolution (640 X 200 points) offers four different colors; colors 4
through 15 are ignored by the palette registers.
When you want the maximum of 16 colors, it's best to zero-out the contents
of the palette registers.
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High-res (640 X 400 points) gives you a choice on only one "color"; bit 0
of palette register 0 is set to the background color. If the bit is cleared, then
the text is black on a light background. A set bit reverses the screen (light
characters, black background). The color register is a read/write register.
$FF82 60
Bit Resolution
1 0
0 0 320 X 200 points, four focal planes
0 1 640 X 200 points, two focal planes
1 0 640 X 400 points, one focal planes
This register sets up the appropriate hardware for the graphic resolution
desired.
SFFStiQQ _ DMA/Disk Controller
$FF8600 reserved
$FF8602 reserved
$FF8604 16-bit FDC access/sector count
The lowest 8 bits access the FDC registers. The upper 8 bits contain no
information, and consistently read 1. Which register of the FDC is used
depends upon the information in the DMA mode control register at
$FF8606. The FDC can also be accessed indirectly.
The sector count-register under $FF8604 can be accessed when the
appropriate bit in the DMA control register is set. The contents of these
addresses are both read/write.
$FF8606 16-bit DMA mode/status
When this register is read, the DMA status is found in the lower three bits of
the register.
Bit 0 0=no error, 1=DMA error
Bit 1 0 = sector count = null, l=sector countonull
Bit 2 Condition of FDC DATA REQUEST signal
Write access to this address controls the DMA mode register.
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Bit 0 unused
Bit 1 0=pin AO is low
l=pin AO is high
Bit 2 0=pin A1 is low
l=pin A1 is high
Bit 3 0=FDC access
1=HDC access
Bit 4 0=access to FDC register
l=access to sector count register
Bit 5 0 , reserved
Bit 6 0=DMA on
l=no DMA
Bit 7 0=hard disk controller access (HDC)
1=FDC access
Bit 8 0=read FDC/HDC registers
l=write to FDC/HDC registers
$FF8609 8-bit
$FF8 60B 8-bit
$FF8 60D 8-bit
DMA basis and counter
DMA basis and counter
DMA basis and counter
high-byte
mid-byte
low-byte
DMA transfer will tell the hardware at which address the data is to be
moved. The initialization of the three registers must begin with the low-byte
of the address, then mid-byte, then high-byte.
$FF88QQ SquM-Que
The YM-2149 has 16 internal registers which can't be directly addressed.
Instead, the number for the desired register is loaded into the select register.
The chosen registers can be read/write, until a new register number is
written to the PSG.
$FF8800 8-bit Read data/Register select
Reading this address gives you the last register used (normally port A), by
which disk drive is selected. This can be accomplished with write-protect
signals, although these protected contents can be accessed by another
register. Port A is used for multiple control functions, while port B is the
printer data port.
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PORT A
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Page-choice signal for double-sided
floppy drive
Drive select signal — floppy drive 0
Drive select signal — floppy drive 1
RS-232 RTS-output
RS-232 DTR output
Centronics strobe
Freely usable output (monitor jack)
reserved
When $FF8800 is written to, the select register of the PSG is alerted. The
information in the bottom four bits are then considered as register numbers.
The necessary four-bit number serves for writing to the PSG.
$FF8802 8-bit Write data
Attempting to read this address after writing to it will give you $FF only,
while BDIR and BC1 are nulls.
Writing register numbers and data can be performed with a single MOVE
instruction.
$FFFAQ0 _ MFP 689Q1
The MFP's 24 registers are found at odd addresses from
$FFFA01-$FFFA2F:
$FFFA0 1
8-bit
Parallel port
$FFFA03
8-bit
Active Edge register
$FFFA05
8-bit
Data direction
$FFFA07
8-bit
Interrupt
enable A
$FFFA0 9
8-bit
Interrupt
enable B
$FFFA0B
8-bit
Interrupt
pending A
$FFFA0D
8-bit
Interrupt
pending B
$FFFA0F
8-bit
Interrupt
in-service A
$FFFA1 1
8-bit
Interrupt
in-service B
$FFFA13
8-bit
Interrupt
mask A
$FFFA15
8-bit
Interrupt
mask B
$FFFA17
8-bit
Vector register
$FFFA1 9
8-bit
Timer A control
$FFFA1B
8-bit
Timer B control
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Abacus Software
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$FFFA1D
8-bit
Timer
C & D control
$FFFA1F
8-bit
Timer
A data
$FFFA2 1
8-bit
Timer
B data
$FFFA23
8-bit
Timer
C data
$FFFA2 5
8-bit
Timer
D data
$FFFA2 7
8-bit
Sync i
character
$FFFA2 9
8-bit
USART
control
$FFFA2B
8-bit
Receiver status
$FFFA2D
8-bit
Transmitter status
$FFFA2F
8-bit
USART
data
See the chapter on the MFP for details on the individual registers.
I/O Port
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Centronics busy
RS-232 data carrier detect - input
RS-232 clear to send - input
reserved
keyboard and MIDI interrupt
FDC and HDC interrupt
RS-232 ring indicator
Monochrome monitor detect
Timers A and B each have an input which can be used by external timer
control, or send a time impulse from an external source. Timer A is unused
in the ST, which means that the input is always available, but it isn't
connected to the user port, so the Centronics busy pin is connected instead.
You can use it for your own purposes.
Timer B is used for counting screen lines in conjunction with DE (Display
Enable).
The timer outputs in A-C are unused. Timer D, on the other hand, sends
the timing signal for the MFP's built-in serial interface.
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Abacus Software
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SFFFCOO Keyboard and MIDI ACIAs
The communications between the ST, the keyboard, and musical
instruments are handled by two registers in the ACIAs.
$FFFC0 0 8-bit
$FFFC02 8-bit
$FFFC0 4 8-bit
$FFFC0 6 8-bit
Keyboard ACIA control
Keyboard ACIA data
MIDI ACIA control
MIDI ACIA data
Figure 1.7-1 I/O Assignments
SFFFCOO
SFFFAOO
2 ACIA* s 6580
MFP 68901
SFF8800
$FF8600
SFF8400
SFF8200
SFF8000
SOUND AY-3-8910
DMA / WD 1770
RESERVED
VIDEO CONTROLLER
DATA CONFIGURATION
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Abacus Software
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Figure 1.7-2 Memory Map of the ATARI ST
$FF FCOO
$FF FHOO
$FF 8800
8600
8400
8200
$FF 8000
16776192
16775680
16746496
16745984
16745472
16744960
16744448
$FE FFFF
$FC 0000
$Ffi 0000
$07 FFFF
$00 0000
192 K
System ROM
128 K ROM
Expansion Cartridge
16711679
16515072
16384000
524287
0
63
Monitor Printer Modem 2 Floppies
Abacus Software
Atari ST Internal
BLOCK DIAGRAM of the ATARI ST
64
6850
Chapter Two
The Interfaces
2.1 The Keyboard
2.1.1 The Mouse
2.1.2 Keyboard commands
2.2 The Video Connection
2.3 The Centronics Interface
2.4 The RS-232 Interface
2.5 The MIDI Connections
2.6 The Cartridge Slot
2.6.1 ROM Cartridges
2.7 The Floppy Disk Interface
2.8 The DMA Interface
Abacus Software
Atari ST Internals
The Interfaces
2.1 The Keyboard
Do you think it's really necessary to give a detailed report on something as
trivial as the keyboard, since keyboards all function the same way? Actually
the title should read "Keyboard Systems" or something similar. The
keyboard is controlled by its own processor. You will soon see how this
affects the assembly language programmer.
The keyboard processor is single-chip computer (controller) from the 6800
family, the 6301. Single chip means that everything needed for operation is
found on a single IC. In actuality, there are some passive components in the
keyboard circuit along with the 6301.
The 6301 has ROM, RAM, some I/O lines, and even a serial interface on
the chip. The serial interface handles the traffic to and from the main board.
The advantage of this design is easy to see. The main computer is not
burdened by having to continually poll the keyboard. Instead it can dedicate
itself completely to processing your programs. The keyboard processor
notifies the system if an event occurs that the operating system should be
aware of.
The 6301 is not only responsible for the relatively boring task of reading the
keyboard, however. It also takes care of the rather complicated tasks
required in connection with the mouse. The main processor is then fed
simply the new X and Y coordinates when the mouse is moved. Naturally,
anything to do with the joysticks is also taken care of by the keyboard
controller.
In addition, this controller contains a real-time clock which counts in
one-second increments.
Abacus Software
Atari ST Internals
In Figure 2.1-1 is an overview of the interface to the 68000. As you see, the
main processors is burdened as little as possible. The ACIA 6850 ensures
that it is disturbed only when a byte has actually been completely received
from the keyboard. The ACIA, by the way, can be accessed at addresses
$FFFC00 (control register) and $FFFC02 (data register). The individual
connection to the keyboard takes place over lines K14 and K15. K indicates
the plug connection by which the keyboard is connected to the main board.
The signal that the ACIA has received a byte is first sent over line 14 to the
MFP 68901 which then generates an interrupt to the 68000. The clock
frequency of 500KHz comes from GLUE. From this results the "odd"
transfer rate of 7812.5 baud.
In case you were surprised that data can also be sent to the keyboard
processor, you will find the solution to the puzzle in Chapter 2.1.2.
The block diagram of the keyboard circuit is found in Figure 2.1-2. The
function is as simple as the figure is easy to read. The processor has 4K of
ROM available. The 128 bytes of RAM is comparatively small, but it is
used only as a buffer and for storing pointers and counters.
The lines designated with K are again the plug connections assigned to the
main board. With few exceptions, the connections for the joystick and
mouse are also put through. K 16 is the reset line from the 68000. K15
carries the send data from the 6850, K14 the send data from the 6301.
The I/O ports 1(0-7), 3(1-7), and 4(0-7) are responsible for reading the
keyboard matrix. One line from ports 3 and 4 is pulled low in a cycle. The
state of port 1 is the checked. If a key is pressed, the low signal comes
through on port 1.
Each key can be identified from the combination of value placed on ports 3
and 4 and the value read from port 1.
If none of the lines of Port 3 and 4 are placed low and a bit of port 1 still
equals zero, a joystick is active on the outer connector 1. The data from
outer connector 0, to which a mouse or a joystick can be connected, does
not come through by chance since it must first be switched through the
NAND gate with port 2 (bit 0). The buttons on the mouse or the joystick
then arrive at port 2 (1 and 2).
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Abacus Software
Atari ST Internals
Figure 2.1-2 Block Diagram of Keyboard Circuit
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Abacus Software
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The assignments of the K lines to the signal names on the outer connector
are found in the next section.
The 6301 processor is completely independent, but it can also be configured
so that it works with an external ROM. Some of the port lines are then
reconfigured to act as address lines. The configuration the processor
assumes (one of eight possibilities) depends on the logical signal placed on
port 2 (bits 0-2) during the reset cycle. All three lines high puts the
processor in mode 7, the right one for the task intended here. But bits 1 and
2 depend on the buttons on the mouse. If you leave the mouse alone while
powering-up, everything will be in order. If you hold the two buttons
down, however, the processor enters mode 1 and makes a magnificent
belly-flop, since the hardware for this operating mode is not provided. You
notice this by the fact that the mouse cursor does not move on the screen if
you move the mouse. Only the reset button will restore the processor.
2.1.1 The Mouse
The construction of this little device is quite simple, but effective.
Essentially, it consists of four light barriers, two encoder wheels, and a
drive mechanism.
The task of the mouse is to give the computer information about its
movements. This information consists of the components: direction on the
X-axis, direction on the Y-axis, and the path traveled on each axis.
In order to do this, the rubber-covered ball visible from the outside drives
two encoder wheels whose drive axes are at angle of 90 degrees to each
other. The one or the other axis rotates more or less, forwards or
backwards, depending on the direction the mouse is moved.
It is no problem to determine the absolute movement on each axis. The
encoder wheels alternately interrupt the light barriers. One need only count
the pulses from each wheel to be informed about the path traveled on each
axis.
Abacus Software
Atari ST Internals
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Abacus Software
Atari ST Internals
It is more difficult when the direction of movement is also required. The
designers of the mouse used a convenient trick for this. There are not one,
but two light barriers on each encoder wheel. They are arranged such that
they are not shielded by the wheel at precisely the same time, but one
shortly after the other. This arrangement may not be so clear in Figure
2. 1.1-1, so we’ll explain it in more detail The direction can be determined
by noticing which of the two light barriers is interrupted first. This is why
the pulses from both light barriers are sent out, making a total of four.
Corresponding to their significance they carry the names XA, XB, YA, YB.
The two contacts which you see on the picture represent the two buttons.
The large box on the picture is a quad operational amplifier which converts
the rather rough light-barrier pulses into square wave signals.
In Figure 2. 1.1 -2 is the layout of the control port on the computer, as you
see it when you look at it from the outside. The designation behind the slash
applies when a joystick is connected and the number in parentheses is the
pin number of the keyboard connector.
PortO
1
XB/UP
(K12)
2
XA/DOWN
(K10)
3
YA/LEFT
(K9)
4
YB/RIGHT
(K8)
6
LEFT BUTTON/FIRE
(Kll)
7
+5V
(K13)
8
GND
(Kl)
9
RIGHT BUTTON
(K6)
Port 1
1
UP
(K7)
2
DOWN
(K5)
3
LEFT
(K4)
4
RIGHT
(K3)
5
Port 0 enable
(K17)
6
FIRE
(K6)
7
+5V
(K13)
8
GND
(Kl)
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Abacus Software
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Figure 2.1. 1-2 Mouse control port
1 5
6 9
2.1.2 Keyboard commands
The keyboard processor "understands" some commands pertaining to such
things as how the mouse is to be handled, etc. You can set the clock time,
read the internal memory, and so on. You can find an application example in
the assembly language listing on page 80 (after command $21).
The "normal" action of the processor consists of keeping an eye on the
keyboard and announcing each keypress. This is done by outputting the
number of the key when the key is pressed. When the key is released the
number is set again, but with bit 7 set. The result of this is that no key
numbers greater than 127 are possible. You can find the assignment of the
key numbers to the keys at the end of this section in figure 2. 1.2-1. In
reality these numbers only go up to 117 because values from $F6 up are
reserved for other purposes. There must be a way to pass more information
than just key numbers to the main processor, information such as the clock
time or the current position of the mouse. This cannot be handled in a single
byte but only in something called a package, so the bytes at $F6 signal the
start of a package. Which header comes before which package is explained
along with the individual commands.
A command to the keyboard processor consists of the command code (a
byte) and any parameters required. The following description is sorted
according to command bytes.
$07
Returns the result of pressing one of the two mouse buttons. A parameter
byte with the following format is required:
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Abacus Software
Atari ST Internals
Bit 0 =1:
Bit 1 =1:
Bit 2 =1 :
Bits 3-7
The absolute position is returned when a
mouse button is pressed. Bit 2 must =0.
The absolute position is returned when a
mouse button is released. Bit 2 must — 0 .
The mouse buttons are treated like
normal keys. The left button is key
number $74, the right is $75.
must always be zero.
$08
Returns the relative mouse position from now on. This command tells the
keyboard processor to automatically return the relative position (the distance
from the previous position) whenever the mouse is moved. A movement is
given when the number of encoder wheel pulses has reached a given
threshold. See also $0B. A relative mouse package looks like this:
1 byte Header in range $F8-$FB. The two lowest
bits of the header indicate the condition
of the two mouse buttons .
1 byte Relative X-position (signed!)
1 byte Relative Y-position (signed!)
If the relative position changes substantially between two packages so that
the distance can no longer be expressed in one byte, another package is
automatically created which makes up for the remainder.
$09
Returns the absolute mouse position from now on. This command also sets
the coordinate maximums. The internal coordinate pointers are at the same
time set to zero. The following parameters are required.
1 word Maximum X coordinate
1 word Maximum Y-coordinate
Mouse movements under the zero point or over the maximums are not
returned.
With this command it is possible to get the key numbers of the cursor ys
instead of the coordinates. A mouse movement then appears to the operating
system as if the corresponding cursor keys had been pressed. These
parameters are necessary:
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Abacus Software
Atari ST Internals
1 byte Number of pulses (X) after which the key
number for cursor left (or right) will be
sent .
1 byte Number of pulses (Y) after which the key
number for cursor up (or down) will be sent.
$0B
This command sets the trigger threshold, above which movements will be
announced. A certain number of encoder pulses elapse before a package is
sent. This functions only in the relative operating mode. The following are
the parameters:
1 byte Threshold in X-direction
1 byte Threshold in Y-direction
$0C
Scale mouse. Here is determined how many encoder pulses will go by
before the coordinate counter is changed by 1. This command is valid only
in the absolute. The following parameters are required:
1 byte X scaling
1 byte Y scaling
$0D
Read absolute mouse position. No parameters are required, but a package of
the following form is sent:
1 byte Header
1 byte Button
Bit 0=1:
Bit 1=1:
Bit 2=1:
Bit 3=1:
= $F7
status
Right button was pressed since the
last read
Right button was not pressed
Left button was pressed since the
last read
Left button was not pressed
From this strange arrangement you can determine that the state of a button
has changed since the last read if the two bits pertaining to it are zero.
1 word Absolute X-coordinate
1 word Absolute Y-coordinate
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Abacus Software
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Set the internal coordinate counter. The following parameters are required:
1 byte =0 as fill byte
1 word X-coordinate
1 word Y-coordinate
$0F
Set the origin for the Y-axis is down (next to the user).
$10
Set the origin for the Y-axis is up.
The data transfer to the main processor is permitted again (see $13).
Any command other than $13 will also restart the transfer.
Turn mouse off. Any mouse-mode command ($08, $09, $0A) turns the
mouse back on. If the mouse is in mode $0A, this command has no effect.
$13
Stop data transfer to main processor.
NOTE: Mouse movements and key presses will be stored as long as the
small buffer of the 6301 allows. Actions beyond the capacity of the butter
will be lost.
Every joystick movement is automatically returned. The packages sent have
the following format:
1 byte
1 byte
Header = $FE or $FF for joystick 0/1
Bits 0-3 for the position (a bit for each
direction) , bit 7 for the button
End the automatic-return mode for the joystick. When needed, a package
must be requested with $16.
Read joystick. After this command the keyboard sends a package as
described above.
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Abacus Software
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$17
Joystick duration message. One parameter is required.
1 byte Time between two messages in 1/100 sec.
From this point on, packages of the following form are sent continuously
(as long as no other mode is selected):
1 byte Bit 0 for the button on joystick 1, bit 1
for that of joystick 0
1 byte Bits 0-3 for the position of joystick 1,
bits 4-7 for the position of joystick 0
NOTE: The read interval should not be shorter than the transfer channel
needs to send the two bytes of the package.
$18
Fire button duration message. The condition of the button in joystick 1 (!) is
continually tested and the result packed into a byte. This means that a
message byte contains 8 such tests, whereby bit 7 is the most recent. The
keyboard controller determines the time between byte fetches by the main
processor. This time is divided into eight equal intervals in which the button
is polled. The polling then takes place as regularly as possible. This mode
remains active until another command is received.
$19
Cursor key simulation mode for joystick 0 (!). The current position of the
joystick is sent to the main processor as if the corresponding cursor keys
had been pressed (as often as necessary). To avoid having to explain the
same things for the following parameters, here are the most important: All
times are assumed to be in tenths of seconds. R indicates the time, when
reached, cursor clicks will be sent in intervals of T. After this the interval is
V. If R=0, only V is responsible for the interval. Naturally, this mechanism
comes into play only when the joystick is held in the same position for
longer than T or R.
1
byte
RX
1
byte
RY
1
byte
TX
1
byte
TY
1
byte
vx
1
byte
VY
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Abacus Software
Atari ST Internals
Turn off joysticks. Any other joystick command turns them on again.
Set clock time. This command sets the internal real-time clock in the
keyboard processor. The values are passed in packed BCD, meaning a digit
0-9 for each half byte, yielding a two-digit decimal number per byte. 1 he
following parameters are necessary:
Year, two digit (85, 86, etc.)
Month, two digit (12, 01, etc.)
Day, two digit (31,01,02, etc.)
Hours, two digit
Minutes, two digit
Seconds, two digit
Any half byte which does not contain a valid BCD digit (such as F) is
ignored. This makes it possible to change just part of the date or clock time.
Read clock time. After receiving this command the keyboard processor
returns a package having the same format as the one described above. A
header is added to the package, however, having the value $FC.
1 byte
1 byte
1 byte
1 byte
1 byte
1 byte
Load memory. The internal memory of the keyboard processor (naturally
only the RAM in the range $80 to $FF makes sense) can be written with this
command. It is not clear to us of what use this is since according to our
investigations (we have disassembled the operating system of the 6301), no
RAM is available to be used as desired. Perhaps certain parameters can be
changed in this manner which are not accessible through legal means.
Here are the parameters:
1 word Start address
1 byte Number of bytes (max. 128)
Data bytes (corresponding to the number)
The interval at which the data bytes will be sent must be less than 20 msec.
1
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Abacus Software
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$21
Read memory. This command is the opposite of $20. These parameters are
required:
1 word Address at which to read
A package having the following format is returned:
1 byte Header 1 =$F6. This is the status header
which precedes all packages containing any
operating conditions of the keyboard
processor. We will come to the general
status messages shortly.
1 byte Header 2 =$20 as indicator that this
package carries the memory contents.
6 bytes Memory contents starting with the address
given in the command.
Here is a small program which we used to read the ROM in the 6301 and
output it to a printer. Here you also see how the status packages arrive from
the keyboard. These are normally thrown away by the 68000 operating
system. Section 3.1 contains information about the GEMDOS and XBIOS
calls used.
start :
prt
equ
0
chout
equ
3
gemdos
equ
1
bios
equ
13
xbios
equ
14
stvec
equ
12
rdm
equ
$21
wrkbd
equ
25
kbdvec
equ
34
term
equ
0
move.w fkbdvec, - (a7)
trap #xbios
addq.l #2,a7
move . 1 d0,a0
lea keyin.al
move . 1 dO.savea
move.l stvec (aO) , save
80
Abacus Software
Atari ST Internals
loop:
wait :
buf out :
by tout :
hexout :
chrout
exit :
move . 1
al, stvec (aO)
move .w
#$f 000 , d4
move .w
d4,tbuf+l
bsr
keyout
cmpi .b
rbuf
beq
wait
moveq.w
#5,d6
bsr
bufout
addq . w
#6,d4
bmi
loop
bra
exit
lea
rbuf+2, a4
move .b
(a4) +, dO
bsr
hexout
dbra
d6, bytout
rts
movea.w
d0,al
lsr .b
#4 , dO
andi .w
#15, dO
lea
table, a3
move .b
0 (a3,d0) ,d2
lsl .w
#8,d2
move . w
al,d0
andi .w
#15, dO
move .b
0 <a3,d0) ,d2
move .w
d2,d0
move .w
d2,-(a7)
lsr .w
=#:
CO
a
o
bsr
chrout
move ,w
(a7) +, dO
bsr
chrout
move .b
#" " , dO
move .w
dO,- (a7)
move . w
#prt, - (a7)
move .w
#chout, - (a7)
trap
#bios
addq . 1
#6,a7
rts
movea
savea, aO
move . 1
save, stvec (aO)
Starting address
Current address
Ending address?
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Abacus Software
Atari ST Internals
move . w
Iterm, - (a7)
trap
tgemdos
keyout :
move .b
rbuf
pea
tbuf
move . w
#2,-(a7)
move . w
twrkbd, - (a7)
trap
#xbios
addq . 1
rts
#8,a7
keyin :
moveq
#7, dO
lea
rbuf, al
repin :
move .b
(aO) + , (al) +
dbra
rts
dO, repin
table :
dc.b
"012345678 9ABCDEF "
rbuf :
ds .b 8
save
ds.l 1
save a
ds .1 1
dummy
ds .b 1
tbuf
dc . b rdm
ds .b
. end
2
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Abacus Software
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$22 • ■ u
Execute routine. With this command you can execute a subroutine in the
6301. Naturally, you must know exactly what it does and where it is
located, so long as you have not transferred it yourself to RAM with $20
(assuming you found some free space). The only required parameters are:
1 word Start address
Status messages
You can at any time read the operating parameters of the keyboard by
simply adding $80 to the command byte with which you would to set the
operating mode (whose parameters you want to know). You then get a
status package back (header- $F6), whose format corresponds exactly to
those which would be necessary for setting the operating mode.
An example makes it clearer: you want to know how the mouse is scaled.
So you send as the command the value $8C (since $0C sets the scaling).
You get the following back:
1 byte Status header =$F6
1 byte X-scaling
1 byte Y-scaling
This is the same format which would be necessary for the command $0C.
For commands which do not require parameters, you get the evoked
command back as such. For example, say you want to know what operating
mode the joystick is in ($14 or $15). You send the value $94 (or $95, it
makes no difference). As status package you receive, in addition to the
header, either $14 or $15 depending on the operating mode of the joystick
handler.
Allowed status checks are: $87, $88, $89, $8A, $8B, $8C, $8F, $90, $92,
$94, $99, and $9A.
In conclusion we have a tip for those for whom the functions of the
keyboard are too meager and who want to give it more "intelligence . The
processor 6301 is also available in "piggy-back" version, the 63P01
(Hitachi). This model does not have ROM built in, but has a socket on the
top for an EPROM of type 2732 or 2764 (8K!). You can then realize your
own ideas and, for example, use the two joystick connections as universal
4-bit I/O ports, for which you can also extend the command set in order to
access the new functions from the XBIOS as well.
83
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Abacus Software
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2.2 The Video Connection
Without this, nothing would be displayed. You would be typing blind.
You'll notice the many pins on the connection. Naturally more lines are
required for hooking up an RGB monitor than for a monochrome screen,
but seven would be enough. There is also something special about the
remaining lines. In Figure 2.2-1 you find a block diagram in which you can
see how the video connection is tied to the system. The numbering of the
pins is given on the figure on the next page, as you can see, when you look
at the connector from die outside. Here is the pin layout:
1 AUDIO OUT. This connection comes from the amplifier
connected to the output of the sound chip. A high-impedance
earphone can be attached here if you do not use the original
monitor.
2 COMPOSITE VIDEO is the connection from 9-12. This is not
available on the early 520ST or 1040 ST.
3 GPO, General Purpose Output. This connection is available for
your use. The line has TTL levels and comes from I/O port A bit 6
of the sound chip.
4 MONOCHROME DETECT. If this line, which leads to the 17
input of the MFP 68901, is low, the computer enters the
high-resolution monochrome mode. If the state of the line changes
during operation, a cold start is generated.
5 AUDIO IN leads to the input of the amplifier described in 1 and is
there mixed with the output of the sound chip.
6 GREEN is the analog green output of the video shifter.
7 RED. Red output.
8 +12 control voltage for color televisions with video connectors.
Atari 520ST = GROUND.
9 HORIZONTAL SYNC is responsible for the horizontal beam
return of the monitor.
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Figure 2.2-1 Diagram of Video Interface
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Abacus Software
Atari ST Internals
10 BLUE is the analog blue output of the video shifter.
11 MONOCHROME provides a monochrome monitor with the
intensity signal.
12 VERTICAL SYNC takes care of the beam return at the end of the
screen.
13 GROUND.
A tip for the hardware hobbyist:
A plug to fit this connector is not available. If you want to make a plug for
connecting other monitors, simply use a piece of perf board in which you
have soldered pins, since the pins are fortunately organized in a 1/10" array.
Pin 13 is out of order, but it is not needed since pin 8 is also available for
ground.
Figure 2.2-2 Monitor Connector
j
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2.3 The Centronics Interface
A standard Centronics parallel printer can be connected to this interface,
provided that you have the proper cable. As you can see in Figure 2.3-2, the
connection to the system is somewhat unusual. The data lines and the strobe
of the universal port of the sound chip are used. So you find these too on
the picture, in which the other lines, which will not be described in the
section, will not disturb you. They belong to the disk drive and RS-232
interface and are handled there.
Here is the pin description:
I -STROBE indicates the validity of the byte on the data lines
to the connected device by a low pulse.
2-9 DATA
II BUSY is always placed high by the printer when it is not
able to receive additional data. This can have various causes.
Usually the buffer is full or the device is off line.
18-25 GROUND.
All other pins are unused.
A tip for making a cable. Get flat-cable solderless connectors. You need a
type D25-subminiature, a Cinch 36-pin (3M,AMP) and the appropriate
length of 25-conductor flat ribbon cable. You squeeze the connectors on the
cable so that pins 1 match up on both sides (they are connected together).
The other connections then match automatically. Note that there will
naturally be some pins free on the printer side.
Figure 2.3-1 Printer Port Pins
1 3
1
25
1 4
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2.4 The RS-232 Interface
This interface usually serves for communication with other computers and
modems. You can also connect a printer here. Note the description of pin 5!
Figure 2.4-1 shows the connection to the system. Normally you don’t have
to do any special programming to use this interface. It is taken care of by the
operating system. Here the control of the interface is not controlled by a
special IC (UART) as is usually the case, but the lines are serviced more or
less "by hand." The shift register in the MFP is used for this purpose. The
handshake lines however come from a wide variety of sources. Note this in
the following pin description:
1 CHASSIS GROUND (shield)
This is seldom used.
2 TxD
Send data
3 RxD
Receive data
4 RTS
Ready to send comes from I/O port A bit 3 of the sound
chip and is always high when the computer is ready to
receive a byte. On the Atari, this signal is first placed low
after receiving a byte and is kept low until the byte has
been processed.
5 CTS
Clear to send of a connected device is read at interrupt
input 12 of the MFP. At the present time this signal is
handled improperly by the operating system. Therefore it
is possible to connect only devices which "rattle" the line
after every received byte (like the 520ST with RTS). The
signal goes to input 12 of the MFP, but unfortunately is
tested only for the signal edge. You will not have any luck
connecting a printer because they usually hold the CTS
signal high as long as the buffer is not full. There is no
signal edge after each byte, which means that only the
first byte of a text is transmitted, and then nothing.
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7 GND
Signal ground.
8 DCD
Carrier signal detected. This line, which goes to interrupt
input II of the MFP, is normally serviced by a modem,
which tells the computer that connection has been made
with the other party.
20 DTR
Device ready. This line signals to a device that the
computer is turned on and the interface will be serviced as
required. It comes from I/O port A bit 4 of the sound
chip.
22 RI
Ring indicator is a rather important interrupt on 16 of the
MFP and is used by a modem to tell the computer that
another party wishes connection, that is, someone called.
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2.5 The MIDI Connections
The term MIDI is probably unknown to many of you. It is an abbreviation
and stands for Musical Instrument Digital Interface, an interface for musical
instruments.
It is certainly clear that we can't simply hook up a flute to this port. So first
a little history. Music professionals (more precisely: keyboardists,
musicians who play the synthesizer) demanded agreement between the
various manufacturers to interface computers to musical instruments. They
found it absurd to connect complicated set-ups with masses of wire. The
idea was to service several synthesizers from one keyboard.
The tone created was basically analog (and still is, to a degree), so that the
manufacturers agreed that a control voltage difference of IV corresponded
to a difference in tone of 1 octave. This way one could play several devices
under "remote control," but not service them.
This changed substantially when the change was made to digital tone
creation. Here one didn't have to turn a bunch of knobs, there were buttons
to press, whereby the basis for digital control was created.
Some manufacturers got together and designed a digital interface, the basic
commands of which would be the same throughout, but which would still
support the additional features of a given device.
The device is based on the teletype, the current-loop principle, which is not
very susceptible to noise, but significantly faster. The transfer rate is 31250
baud (bits per second). The data format is set at one start bit, eight data bits,
and one stop bit.
An IC can therefore be used for control which would otherwise be used for
RS-232 purposes. You see the connection to the system in figure 2.5-1.
Logically, MIDI is multi-channel system, meaning that 16 devices can be
serviced by one master, or a device with 16 voices. These devices are all
connected to the same line (bus principle). To identify which device or
which voice is intended, each data packet is preceded by the channel
number. The device which recognizes this number as its own then executes
the desired action.
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You may wonder what such an interface is doing in a computer. A computer
can provide an entire arsenal of synthesizers with settings or complete
melodies (sequencer) because of its high speed and memory capacity. It can
also be used to record and store input from a synthesizer keyboard.
For this purpose the ST has the interfaces MIDI-IN and MIDI-OUT. The
interfaces are even supported by the XBIOS so you don't have to worry
about their actual operation.
The current loop travels on pins 4 and 5, out through pin 4 (+) of
MIDI-OUT and in at 5, when a device is connected.
For MIDI-IN the situation is reversed because the current flows in through
pin 4 and back out through pin 5. It goes though something called an
optocoupler which electrically isolates the computer from the sender.
The received data are looped back to MIDI-OUT (pins 1 and 3), which
implements the MIDI-THRU function, although not entirely according to
the standard.
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2.6 The Cartridge Slot
The cartridge slot can be used exclusively for inserting ROM cartridges. Up
to 128K in the address space $FA0000 to $FBFFFF can be addressed. The
reason we stressed the exclusivity of the read access is the following. We
thought it would be practical to outfit a cartridge with RAM and then load
programs into it after the system start which would still remain after a reset.
In order to try this we brought the R/-W signal to the outside. The
experience taught us, however, that a write access to these addresses creates
a bus error. The GLUE takes care of this. As you see, nothing is left to
chance in the Atari.
Figure 2.6-1 The Cartridge Slot
1
=
+ 5VDC
2
1
=
Address
8
2
=
+ 5VDC
2
2
=
Address
14
3
=
Data 14
2
3
=
Address
7
4
=
Data 15
2
4
=
Address
9
5
=
Data 12
2
5
=
Address
6
6
=
Data 13
2
6
-
Address
10
7
=
Data 10
2
7
-
Address
5
8
=
Data 11
2
8
=
Address
12
9
—
Data 8
2
9
=
Address
11
1
0
=
Data 9
3
0
=
Address
4
1
1
=
Data 6
3
1
-
ROM Select
3
1
2
=
Data 7
3
2
=
Address
3
1
3
=
Data 4
3
3
=
ROM Select
4
1
4
=
Data 5
3
4
=
Address
2
1
5
=
Data 2
3
5
as
Dpper
Data
Strobe
1
6
=
Data 3
3
6
as
Address
1
1
7
=
Data 0
3
7
=
Lower
Data
Strobe
1
8
=
Data 1
3
8
G N D
1
9
=
Addre s s
13
3
9
=
GHD
2
0
=
Addre s s
15
4
0
=
G N D
Position :
1
2
3 9
40
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2.6.1 ROM Cartridges
We want to spend this section telling you how a program is put into ROM,
as well as how the operating system recognizes and loads such a program.
These cartridges are technically feasible, since many manufacturers are now
making ROM cartridge boards and programming devices for the ST
computers.
The most important aspect is the first longword in ROM, which must
contain an index number, or "magic number". This is read when the system
start occurs — it checks to see whether there is a program cartridge or a
diagnostic cartridge plugged into the cartridge port. The former must
contain the index number $ABCDEF42, the latter the index number
$FA52255F.
We wouldn't want to go any farther with the diagnostic cartridge. It should
be enough that the operating system jumps to immediately test the address
$FA0004 without initializing GEMDOS. You won't get any system
processes anyway from this cartridge.
The program cartridges are what interest us. We can call up several
programs from a ROM module of this type. Every program must have an
introductory section, or application header, to be started by the operating
system. The first must begin right after the magic number (from $FA0004),
and must be made up of the following:
1 longword:
Address of the next header, when multiple programs reside in one cartridge.
The header of the last (or only) program must contain $00000000.
1 longword:
Initialization code. This is where GEMDOS gets information, first about the
handling of the program. In particular, this longword is made up of an
address which points to the initialization routine (when needed). The most
significant byte in this longword states at which point in time this routine
should jump.
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Atari ST Internals
This is arranged as follows:
BIT
0 The routine will be executed before the interrupt vectors,
video RAM, etc., is installed.
1 The routine will be executed before GEMDOS is initialized.
3 The routine will be executed before GEMDOS is loaded.
NOTE: This function is not accessible to computers which
have GEMDOS in ROM!
5 Character which indicates that the program should be handled
as an accessory.
6 Character which identifies the program as a .TOS type, and
not requiring the GEM system. _
7 Character which identifies the program as a .TTP type, and
requiring starting parameters.
1 longword:
Starting address of the program, i.e. where it would start if you
double-clicked it.
1 word:
Time in DOS format; has no meaning during runtime.
1 word:
Date in DOS format, see the previous entry.
1 longword:
Program length in bytes; has no meaning during runtime.
String:
Program name in explanatory text. The program name is inserted according
to normal conventions, i.e., up to 8 characters, a period (.), and three
characters after the period. NOTE: The string absolutely must be concluded
by $00.
So, that's it. As for the rest: We've neglected to give you any information
on clicking. Some program cartridges have their own icons, similar to a
disk drive icon. Click this icon. It will show the programs contained in the
cartridge; you may then start the desired program.
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2.7 The Floppy Disk Interface
The interface for floppy disk drives is conspicuous because of the unusual
connector, a 14-pin DIN connector. All of the signals required for the
operation of two disk drives are available on it.
You know most of the signals from the description of the disk controller
1772, since nine of the available connections are connected to the controller
either directly or through a buffer. Only the drive select 1 and drive select 2
signals and the side 0 select are not derived from the disk controller. These
signals come from port A of the sound chip.
Pinout of the disk connector:
1 READ DATA
2 SIDE 0 SELECT
3 GND
4 INDEX
5 DRIVE 0 SELECT
6 DRIVE 1 SELECT
7 GND
8 MOTOR ON
9 DIRECTION IN
10 STEP
11 WRITE DATA
12 WRITE GATE
13 TRACK 00
14 WRITE PROTECT
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2.8 The DMA Interface
This 19-pinjack can handle up to 8 DMA-compatible devices. These include
hard disks, networks, and even coprocessors. The communications
between the external devices and the ST run at a speed of up to 1 million
bytes per second.
1-8
9
10
11
12
13
14
15
16
17
18
19
D0-D7
Bidirectional data lines
CS
Chip Select, low-active. This line is activeated from the computer
when either commands are sent to the device, or status bytes are read
from there. If DMA transfer is in process, the signal is in a wait state.
IRQ
Interrupt Request, low=active. This signal is produced by the device,
and tells the computer that an action is done (e.g., DMA transfer).
GND
RST
Reset, low^active.
GND
ACK
Acknowledge, low-active. This signal only has meaning during DMA
transfer. This indicates the device to the computer's DMA controller,
depending on the data direction, whether a byte is received from the
device or whether a legal data byte lies on the bus.
GND
A1
Address 1. This signal tells the device’s DMA controller whether the
device address is set on bus with all commands (Al=low) or whether
parameter bytes are handled (usually 5 parameter bytes; Al=high).
GND
R/W
Read/Write. This line also controls the controller, and is valid only
when initializing. Write(=low): Command bytes snet; Read (=high):
Waiting for a status byte.
DRQ
Data Request, low=active. This signal is produced from the device
only during DMA transfer, depending upon data direction, when it can
receive a byte from the controller; or otherwise, set a byte on the bus.
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There are two different methods of transfer. One is a computer controlled
data transfer using the Al, CS and R/W lines. The other transfer of data,
controlled from the device itself (the DMA transfer), runs without the
computer with the help of the DRQ and ACK lines.
A connection can be seen between the chip description of the DMA
controller, and the reset routine in the operating system, which checks for
all eight possible DMA devices.
Figure 2.8-1 DMA Port
19 11
Figure 2.8-2 DMA Connections
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Chapter 3
\
The ST Operating System
3.1 The GEMDOS
3.1.1 Memory, files and processes
3.2 The BIOS Functions
3.3 The XBIOS
3.4 The Graphics
3.4.1 An overview of the line- A variables
3.4.2 Examples for using the line-A opcodes
3.5 The Exception Vectors
3.5.1 The line-F emulator
3.5.2 The interrupt structure of the ST
3.6 The ST VT52 Emulator
3.7 The ST System Variables
3.8 The 68000 Instruction Set
3.8.1 Addressing modes
3.8.2 The instructions
3.9 The BIOS listing
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The ST Operating System
GEMDOS-what is it? Is it in the ST? The operating system is supposed to
be TOS, though. Or is it CP/M 68K? Or what?
These questions can be answered with few words. The operating system in
the ST is named TOS— Tramiel Operating System-after the head of Atari.
This TOS, in contrast to earlier information has nothing to do with CP/M
68K from Digital Research. At the start of development of the ST, CP/M
68K was implemented on it, but this was later changed because CP/M 68K
is not exactly a model of speed and efficiency. A 68000 running at 8MHz
and provided with DMA would be slowed considerably by the operating
system.
At the beginning of 1985, Digital Research began developing a new
operating system for 68000 computers, which would include a user-level
interface. This operating system was named GEMDOS. It is exactly this
GEMDOS which makes up the hardware-independent part of TOS. Like
CP/M, TOS consists of a hardware-dependent and a hardware-independent
part. The hardware-dependent part is the BIOS and the XBIOS, while the
hardware-independent part is called GEMDOS. A large number of functions
are built into GEMDOS, through which the programmer can control the
actual input/output functions of the computer. Functions for keyboard input,
text output on the screen or printer, and the operation of the various other
interfaces are all present. Another quite important group contains the
functions for file handling and for logical file and disk management.
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3.1 The GEMDOS
When you look at the functions available under GEMDOS, you will
eventually come to the conclusion that the whole thing is not really new. All
the functions in GEMDOS are very similar to the functions of the MS-DOS
operating system. Even the functions numbers used correspond to those of
MS-DOS. But not all MS-DOS functions are implemented in GEMDOS.
Especially in the area of file management, only the UNIX compatible
functions are implemented in GEMDOS. The "old" block-oriented
functions which are included in MS-DOS to maintain compatibility with
CP/M are missing from GEMDOS. Also, special functions relating to the
hardware of MS-DOS computers (8088 processor) are missing.
Another essential difference between MS-DOS and GEMDOS is that for
GEMDOS calls as well as for the BIOS and XBIOS, the function number,
the number of the desired GEMDOS routine, and the required parameters
are placed on the stack and are not passed in the registers. The 68000 is
particularly suited to this type of parameters passing. GEMDOS is called
with trap #1 and the function is executed according to the contents of
the parameter list. After the call, the programmer must put the stack back in
order himself, by clearing the parameters from memory.
The basic call of GEMDOS functions differs from the BIOS and XBIOS
calls only in the trap number.
In regard to all GEMDOS calls, it must be noted that registers DO and AO
are changed in all cases. If a value is returned, it is returned in DO, or DO
may contain an error number, and after the call AO (usually) points to the
stack address of the function number. Any parameters required in DO or AO
must be placed there before GEMDOS is called.
The remainder of this section describes the individual GEMDOS functions.
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$00 TERM
C: void PtermO ()
Calling GEMDOS with function number 0 ends the running program and
returns to the program from which it was started. For applications
(programs started from the desktop), control is returned to the desktop. If
the program was called from a different program, control is passed back to
the calling program. This point is important for chaining program segments.
clr.w -(sp)
trap
$01 CONIN
C: long CconinO
CONIN gets a single character from the keyboard. The routine waits until a
character is available. The character read from the keyboard is returned in
the DO register. The ASCII code of the pressed key is returned in the low
byte of the low word, while the low byte of the high word of the register
contains the scan code from the keyboard. This is important for reading
keys which have no ASCII code, such as the 10 function keys or the editing
keys. These keys return the ASCII value zero when pressed.
The scan code can be used to determine if the keypad or the main keys were
pressed. These keys have identical ASCII codes, but different scan codes.
In addition, Shift status can be determined from the upper eight bits (bits 24
to 31) by calling Cconin. In this case, bits 24-31 correspond to bits 0 to 7 m
BIOS function 1 1 ("kbshift"). The information can only be sent on a Cconin
call when bit 3 of the memory location "conterm" (address $484) is set. If
this bit is unset, then the shift bits after Cconin are deleted.
Cconin does not recognize <ControlxC>.
move.w #l,-(sp)
trap #1
addq.l #2,sp
Function number on the stack
Call GEMDOS
Correct stack
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Atari ST Internals
$02 CONOUT
C: void Cconout (c)
int c ;
CONOUT also known as Cconout, represents the simplest and most
primitive character output of GEMDOS. With this function only one
character is printed on the screen. The character to be displayed is placed on
the stack as the first word. The ASCII value of the character to be printed
must be in the low byte of the word and the high byte should be zero:
The character printed by CONOUT is sent to device number 2, the normal
normal! °Ut^Ut‘ ^'ontro^ characters and escape sequences are interpreted
move . w #65, -(sp)
move . w #2, - (sp)
trap #1
addq.l #4,sp
Output an A
CONOUT
Call GEMDOS
Correct stack
$03 AUXILIARY INPUT
C : int Cauxin ( )
Tfie RS-232 interface of the ST goes under the designation "auxiliaiy port".
A character can be read from the interface with the Cauxin function. The
function returns when a character has been completely received. The
character is returned in the lower eight bits of register DO.
move . w #3, - (sp)
trap #1
addq.l #2,sp
Cauxin
Call GEMDOS, output character
Correct stack
Character in DO
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$04 AUXILIARY OUTPUT
C: void Cauxout (c)
int c ;
A character can be transmitted over the serial interface, similar to the input
of characters. With this function the programmer should clear the upper
eight bits of the word and pass the character to be sent in the lower eight
bits.
An A should be output
Cauxout
Call GEMDOS, output character
Correct stack
move.w #$41, -(sp)
move.w #4,-(sp)
trap #1
addq .1 # 4 , sp
$05 PRINTER OUTPUT
C: void Cprnout(c)
int c;
PRINTER OUTPUT is the simplest method of operating a printer connected
to the Centronics interface. One character is printed with each call.
An important part of PRINTER OUTPUT is the return value in DO. If the
character was sent to the printer, the value - 1 ($FFFFFFFF) is returned m
DO If after 30 seconds, the printer was unable to accept the character (not
turned on, OFF LINE, no paper, etc.), GEMDOS returns a time out to the
program. DO then contains a zero.
move . w
move . w
trap
addq . 1
tst . w
beq
#65, -(sp)
#5, - (sp)
#1
#4, sp
DO
Output an A
Function number
Call GEMDOS, output character
Correct stack
Affect flags
printererror
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$06 RAWCONIO
C: long Crawio(c)
int c ;
RAWCONIO is a somewhat unusual mixture of keyboard input and screen
output; it also receives a parameter on the stack.
The keyboard is tested with a function value of $FF. If a character is
present, the ASCII code and scan code are passed to DO as described for
CONJN. If no key value is present, the value zero is passed as both the
ASCII code and the scan code in DO. The call to RAWCONIO with
parameter $FF is comparable to the BASIC INKEY$ function.
If a value other than $FF is passed to the function, the value is interpreted as
a character to be printed and it is output at the current cursor position. This
output also interprets the control characters and escape sequences properly.
START:
move . w
#$ff,-(sp)
Function value test keyboard
move . w
#6, - (sp)
Function number
trap
#1
Call GEMDOS, test keyboard
addq . 1
#4, sp
Correct stack
tst . w
DO
Character arrived?
beq
START
Not yet
cmp .b
#3, DO
AC selected as the end marker
beq
END
move
DO, - (sp)
Character for output on the stack
move
#6, - (sp)
Function number
trap
#1
Call GEMDOS, test keyboard
addq . 1
#4, sp
Correct stack
bra
START
Get new character
$07 DIRECT CONIN WITHOUT ECHO
C: long CrawcinO
The function $07 differs from $01 only in that the character received from
the keyboard is not displayed on the screen. It waits for a key iust as does
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move . w
#8,- (sp)
Cauxin
trap
#1
Call GEMDOS,
output character
addq . 1
#2, sp
Adjust stack
■
Character in
DO
$08 CONIN WITHOUT ECHO
C: long CnecinO
Both function $08 and function $07 have exactly the same effect. The
reason for this seemingly nonsensical behavior lies in the abovementioned
compatibility to MS-DOS. Under MS-DOS these two functions are different
in that with $08, certain keys not present on the ATARI are evaluated
correctly, while this evaluation does not take place with function $07.
move . w #8,-(sp) Cauxin
trap #1 Call GEMDOS, output character
addq.l #2,sp Adjust stack
. Character in DO
$09 PRINT LINE
C: void Cconws(c)
int c ;
You are already familiar with functions that output individual characters on
the screen (see CONOUT and RAWCONIO). PRINT LINE offers you an
easy way to output text. An entire string can be printed at the current cursor
position with this function. To do this, the address of the string is placed on
the stack as a parameter. The string itself is concluded with a zero byte.
Escape sequences and control characters can also be displayed with this
function.
After the call, DO contains the number of characters which were printed.
The length of the string is not limited.
Ill
Abacus Software
Atari ST Internals
move . 1
#text , - (sp)
Address of the string on the stack
move
#$09, - (sp)
Function number PRT LINE
trap
#1
Call GEMDOS
addq . 1
#6, sp
Clear the stack
text
.dc.b 'This
is the string to be printed' , $0D, $0A, 0
$0A READLINE
C; void Cconrs (buf )
char *buf ;
READLINE is a very easy-to-use function for reading characters from the
keyboard. In contrast to the "simpler" character-oriented input functions, an
entire input line can be taken from the keyboard with READLINE. The
characters entered are displayed on the screen at the same time.
The address of an input buffer is passed to the function as the parameter.
The value of the first byte of the input buffer determines the maximum
length of the input line and must be initialized before the call. At the end of
the routine, the second byte of the buffer contains the number of characters
entered. The characters themselves start with the third byte.
The routine used by READLINE for keyboard input is quite different from
the character-oriented console inputs. Escape sequences are not interpreted
during the output. Only control characters like <ControlxH> (backspace)
and <ControlxI> (TAB) are recognized and handled appropriately. The
following control characters are possible:
AC
Ends input and program ( ! )
AH
Backspace one position
AI
TAB
AJ
Linefeed, end input
AM
CR, end input
AR
Entered line is printed in :
new
line
AU
Don't count line, start new
line
AX
Clear line, cursor at start
of
line
A function like AH (deleting a character entered) is useful, but for large
programs you should write your own input routine because AC is very
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"dangerous." Unlike CP/M, the program will be ended even if the cursor is
not at the very start of the input line.
If more characters are entered than were indicated in the first byte of the
buffer at the initialization, the input is automatically terminated. If the input
is terminated by ENTER, AJ, or AM, the terminating character will not be
put in the buffer.
After the input, DO contains the number of characters entered, excluding
ENTER, which can be found at buffer+1.
pea buffer
move #$0A,-(sp)
trap #1
addq. 1 #6, (sp)
buffer dc.b 20
dc .b 0
ds . b 20
Address of the input buffer
Function number
Make room on stack
We want a maximum of 20 characters
Number of given characters
of the input buffer
$0B CONSTAT
C: int CConisO
All key presses are first stored in a buffer in the operating system. This
buffer is 64 bytes in length. The key values stored there are taken from the
buffer when a call to a GEMDOS output routine is made.
CONSTAT can be used to check if characters are stored in the keyboard
buffer. After the call, DO contains the value zero or $FFFF. A zero in DO
indicates that no characters are available.
testloop :
move #$0B,-(sp)
trap #1
addq. 1 #2, (sp)
tst.w DO
beq testloop
Function number
Make room on stack
Character available?
NO, then look again
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$0E SETDRV
C: long Dsetdrv(drv)
int drv;
The current drive can be determined with the function SETDRV. A 16-bit
parameter containing the drive specification is passed to the routine. Drive A
is addressed with the number 0 and drive B with the number 1.
After the call, DO contains the number of the drive active before the call.
move #$2,-(sp) Drive C, e.g. RAMdisk
move #$0E,-(sp) Function number
trap #1
addq.l #4, (sp) Make room on stack
Previous current drive in DO
$10 CONOUT STAT
C: int CconosO
CONOUT STAT returns the console status in DO. If the value $FFFF is
returned, a character can be displayed on the screen. If the returned value is
zero, no character output is possible on the screen at that time. Incidentally,
all attempts failed at creating a not-ready status at the console. The only
imaginable possibility for the not-ready status would be if the output of the
individual bit pattern of a character was interrupted and the interrupt routine
itself tried to output a character. This case could not, however, be created.
move #$10, -(sp) Function number
trap #1
addq.l #2, (sp) Make room on stack
Always $FFFF in DO
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$11 PRTOUT STAT
C: int CprnosO
This function returns the status, the condition of the Centronics interface. If
no printer is connected (or turned off, or off line), DO contains the value
zero after the call to indicate "printer not available." If, however, the printer
is ready to receive, DO contains the value $FFFF.
move #$11, -(sp) How's the printer doing?
trap #1
addq.l #2, (sp) Make room on the stack
tst dO
beq printererror Go here if not ready
$12 AUXIN STAT
C: int Cauxis(c)
AUXIN STAT shows whether a character is available from the serial
interface receiver ($FFFF) or not ($0000). The value is returned in DO.
waitloop :
move #$12, -(sp)
trap #1
addq. 1 #2, (sp)
tst dO
bne waitloop
We wait for a character
from the serial interface
Make room on the stack
Is there a character there?
No, not yet
$13 AUXOUT STAT
C: int Cauxos ()
AUXOUT STAT gives information about the state of the serial bus. A value
of $FFFF indicates that the serial interface can send a character, while zero
indicates that no characters can be sent at this time.
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waitloop:
move #$13, -(sp)
trap #1
addq. 1 #2, (sp)
tst dO
bne waitloop
Wait for a character
from the serial interface
Make room on the stack
Received one yet?
No, not yet
$19 CURRENT DISK
C : int Dgetdrv ( )
For many applications it is necessary to know which drive is currently
active. The current drive can be determined by the function $19. After the
call, DO contains the number of the drive. The significance of the drive
numbers is the same as for $0E, SET DRIVE (0=A, 1=B).
Which drive is active?
It will be sent over
the serial interface
Make room on the stack
There will now be a character in
DO between 'A' and 'P'
move #$19, -(sp)
trap #1
addq.l #2, (sp)
ADD DO, 'A'
$1A SET DISK TRANSFER ADDRESS
C: void Fsetdta (buf )
char *buf ;
The disk transfer address is the address of a 44-byte buffer required for
various disk operations (especially directory operations). Along with the
GEMDOS functions SEARCH FIRST and SEARCH NEXT are examples
for using the DTA.
move.l #DTADDRESS, - (sp) Address of the 44-byte DTA buffer
move.w #$la,-(sp) Function number SET DTA
trap #1 Set DTA
addq.l #6,sp Clean up the stack
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$20 SUPER
This function is especially interesting for programmers who want to access
the peripherals or system variables available only in the supervisor mode
while running a program in the user mode. After calling this function from
user mode, the 68000 is placed in the supervisor mode. In contrast to the
XBIOS routine for enabling the supervisor mode, additional GEMDOS,
BIOS, and XBIOS calls can be made after a successful SUPER call.
Calling the SUPER function with a value of -1L ($FFFFFFFF) tells us the
processor's current operating mode. If the result in DO after the call is 0,
the processor is in user mode. A value of $0001 signifies that the processor
is in supervisor mode. Switching modes is not carried out yet.
A program in user mode can call the SUPER function with a zero on the
stack. In this case, the supervisor mode will be turned on. The supervisor
stack pointer points to the current value of the user stack, and the original
value of the supervisor stack is in DO. This value must be stored in the
program to later return to the user mode. If the change to user mode is not
made before the end of the program, the odds of a system crash are good.
If a value other than zero is passed to the SUPER function the first time it is
called, this value is interpreted as the desired value of the supervisor stack
pointer. In this case as well, DO contains the original value of the supervisor
stack pointer, which the program should save.
As mentioned above, the user mode should be reenabled before the end of
the program. This change of modes requires setting the address used by the
supervisor stack pointer back to its original value.
The SUPER function differs from all other GEMDOS functions in one very
important respect. Under certain circumstances, this call can also change the
contents of A1 and Dl. If you store important values in these registers, you
must save the values somewhere before calling the SUPER function.
clr . 1
- (sp)
move . w
#$20, -(sp)
trap
#1
add. 1
$6, sp
move . 1
dO , _S AVE_£
The 68000 is in the user mode
User stack becomes supervisor stack
Call SUPER
Supervisor mode is active after TRAP
DO = old supervisor stack
Save value
Here processing can be
done in the supervisor mode
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move.l _SAVE_SSP , - ( sp) Old supervisor stack pointer
move . w #$20, -(sp) Call SUPER
trap #1 Now we are back in the user mode
add.l #6,sp
$2A GET DATE
C: int TgetdateO
You have no doubt experimented with the status field at one time or another.
Among other functions, the status field contains a clock with time and date.
It can be useful for some applications to have that data available. The date
can be easily determined by GET DATE. This call requires no parameters
and puts the date in the low word of register DO. It is thoroughly encoded,
though, so the result in DO must be prepared to get the correct date.
The day in the range 1 to 3 1 is coded in the lower five bits. Bits 5 to 8
contain the month in the range 1 to 12, and the year is contained in bits 9 to
15. The range of these "year bits" goes from 0 to 1 19. The value of these
bits must be added to the value 1980 to get the actual year. The date
12/12/1992, for example, would be %0001 100.1 100.01 100 in binary, or
$198C in DO. The lengths of the three fields are marked with periods.
move
#$2a, - (sp)
We
want to get some data
trap
#1
addq . 1
#2, (sp)
move
dO , dl
Store
result in Dl for now
and
#%11111
, DO
Mask ■
the day bits and
move
dO , DAY
store
them
LSR
#5, dl
Shift
the 5 day bits
move
dl, dO
and
#%1111,
dO
and mask the month bits
move
DO, MONTH
Store
the month number
LSR
#4, dl
Shift
the month bits
move
dl, YEAR
Year .
is in Dl
DAY
ds . w
1
MONTH
ds . w
1
YEAR
ds . w
1
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$2B SET DATE
C: int Tsetdate (date)
int date ;
The clock time and date can also be set from application programs. This is
particularly interesting for programs which use the date and/or clock time.
An example of this would be invoice processing in which the current date is
inserted in the invoice. Such programs can then ask the user to enter the
date. This avoids the problems that occur if the user forgets to set the date
and clock time on the status field beforehand.
The date must be passed to the function SET DATE in the same format as it
is received from GET DATE, bits 0-4 = day, bits 5-8 = month, bits 9-15 =
year-1980.
move . w #%101101011001,-(sp) Set date to 10/25/1985
move.w #$2b,-(sp) Function number of SET DATE
trap #1 Set date
addq.l #4,sp Repair stack
$2C GET TIME
C: int TgettimeO
The function GET TIME returns the current (read: set) time from the
GEMDOS clock. Similar to the date, the clock time is coded in a special
pattern in individual bits of the register DO after the call. The seconds are
represented in bits 0-4. But since only values from 0 to 31 can be
represented in 5 bits, the internal clock runs in two second increments. In
order to get the correct seconds-result the contents of these five bits must be
multiplied by two. The number of minutes is contained in bits 5 to 10, while
the remaining bits 11-15 give information about the hour in 24-hour format.
waitloop :
move #$2c,-(sp)
trap #1
addq.l #2,sp
move dO , dl
Is it noon yet?
Get the time from GEMDOS
Store result in Dl
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and
#$1111, DO
Store seconds in steps
move
DO, SEC
of two
LSR
#4, D1
Shift 4 second bits
bne
waitloop
No, not yet
$2D SET TIME
C: int Tsettime (time)
int t ime ;
It is also possible to set the clock time under GEMDOS. The function SET
TIME expects a 16- bit value (word) on the stack, in which the time is coded
in the same form as that in which GET TIME returns the clock time.
When GEMDOS has the given time, DO returns the value 0; otherwise the
value returned is $FFFFFFFF. GEMDOS handles time much as it does the
date. Time changes through GEMDOS cannot be conveyed through the
XBIOS. Select either XBIOS or GEMDOS. If you cross the two, you will
end up with some very unpleasant complications.
move . w #%1000101010111101,-(sp) Clock time 17:21:58
move . w #$2D,-(sp) Function # of GET TIME
trap #1 Set date
addq.l #4,sp Repair stack
$2F GET DTA
C: long FgetdtaO
The function $2F is the counterpart of SET DTA ($1A). A call to GET DTA
returns the current disk transfer buffer address in DO. A description of this
buffer is found with the functions SEARCH FIRST and SEARCH NEXT.
move #$2f,-(sp) Function number Fgetdta
trap #1 Get DTA
addq.l #2fsp
move.l dO , DTAPOINTER and mark for later
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$30 GET VERSION NUMBER
C: int SversionO
Calling this function returns in DO the version number of GEMDOS. In the
version of GEMDOS currently in release, this question is always answered
with $0D00, corresponding to version 13.00. Official Atari documentation
claims that a value of $0100 should be returned for this version, though
perhaps the value should indicate that the present GEMDOS version is the
$D = diskette version.
move #30, -(sp)
trap #1
addq.l #2,sp
cmp #$1300, dO
bne not tos
Look to see which
version we have
The recognized version?
It can't be given
$31 KEEP PROCESS
C: void Ptermres (keepcnt, retcode)
long keepcnt;
int retcode;
This function is comparable to the GEMDOS function TERM $00. The
program is also ended after a call to this function. $3 1 does differ from $00
in several important points.
After processing TRAP#1, like TERM, control is passed back to the
program which started the program just ended. In contrast to TERM, a
termination condition can be communicated to the caller. While TERM
returns the termination value zero (no error), zero or one may be selected as
the termination value for $31. A value other than zero means that an error
occurred during program processing.
Another essential point lies in the memory management of GEMDOS. When
a program is started, the entire available memory space is made available to
it. If the program is ended with TERM, the memory space is released and
made available to GEMDOS. The entire area of memory released is also
cleared, filled with zeros. The program actually physically disappears from
the memory. With function $31, however, an area of memory can be
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protected at the start address of the program. This memory area is not
released when the program is ended and it is also not cleared. The program
could be restarted without having to load it in again.
Practical applications for Ptermres() are spoolers, RAM disks and other
utilities which are installed once and remain in memory for storage or
processing. At the same time, such programs must be ended correctly after
installation to allow other programs to be loaded and started.
KEEP PROCESS is called with two parameters. The example program
shows the parameter passing. It is also important that memory additionally
reserved for programs be Malloc not be freed up. If files are opened by
PtermresQ at that time, these will be closed by GEMDOS.
move . w #0, - (sp)
move . 1 #$1000, -(sp)
move . w #$31, -(sp)
trap #1
Error code no error, else 1
Protect $1000 bytes at program start
Function number, end program
. . . .now.
This time, don’t clear the stack!
$36 GET DISK FREE SPACE
C: void Dfree (buffer, drive)
long *buffer
int drive
It can be very important for disk-oriented programs to determine the amount
of free space on the diskette, then warn the user to change disks. "Disk
full" messages or even data loss can then be avoided.
Function $36, Dfree(), returns this information. The number of the desired
disk drive and the address of a 16-byte buffer must be passed to the
function. If the value 0 is passed as the drive number, the information is
fetched from the active drive, a 1 takes the information from drive A, and a
2 from drive B.
The information passed in the buffer is divided into four long words. The
first longword contains the number of free allocation units. Each file, even
if it is only eight bytes long, requires at least one such allocation unit.
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The second longword gives information about the number of allocation
units present on the disk, regardless of whether they are already used or are
still free. For the "small" single-sided diskettes this value is $15C or 351,
while the double-sided disks have $2C7 = 711 allocation units.
The third longword contains the size of a disk sector in bytes. For the Atari
this is always 512 bytes ($200 bytes).
The last longword is the number of physical sectors belonging to an
allocation unit. This is normally 2. Two sectors form one allocation unit.
The amount of free disk space can be easily calculated from this data.
move . w
#0, - (sp)
Information from the active drive
pea
BUFFER
Address of the 16-byte buffer
move
#$36, -(sp)
Function number
trap
#1
addq. 1
#6, sp
Clean up stack
BUFFER:
f real :
-ds . 1
1
Free allocation units
total :
• ds . 1
1
Total allocation units
bps :
• ds . 1
1
Bytes/physical sector
pspal :
. ds.l
1
Phys. sectors/alloc, u
$39 MKDIR
C: int Dcreate (path)
char *path;
A subdirectory can be created from the desktop with the menu option "NEW
FOLDER". Such a subdirectory can also be created from an application
program with a call to $39.
In order to create a new folder, the function $39 is given the address of the
folder name, also called the pathname. This name may consist of 8
characters and a three-character extension. The same limitations apply to
pathnames as do to filenames. The pathname must be terminated with a zero
byte when calling MKDIR.
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After the call, DO indicates whether the operation was performed
successfully. If DO contains a zero, the call was successful. Errors are
indicated through a negative number in DO. At the end of this chapter you
will find an overview of all of the error messages occurring in connection
with GEMDOS functions.
move . 1 pathname
move #$39, -(sp)
trap #1
addq.l #6,sp
tst.w dO
bne error
pathname :
.dc.b 'private .dat 0
$3 A RMDIR
C: int Ddelete (path)
char *path;
A subdirectory created with MKDIR can be removed with $3A. As before,
the pathname, terminated with a zero, is passed to RMDIR. The error
messages also correspond to those for MKDIR, with zero for success or a
negative value for errors. An important error message should be mentioned
at this point. It is the message -36 ($FFFFFFCA). This is the error message
you get when the subdirectory you are trying to remove contains files.
Only empty subdirectories can be removed with RMDIR. If you get an
error, erase directory files with UNLINK ($41), then call RMDIR again.
Address of the pathname
Function number
Repair stack
Error occurred?
Apparently
pea pathname
move.w #$3A,-(sp)
trap #1
addq.l #6,sp
tst.w DO
bne era sub dir
Address of the pathname
Function #
Repair stack
Is there an error?
It appears that way
pathname :
.dc.b ' tmpfiles .a_z ' , 0
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$3B CHDIR
C: int Dsetpath (path)
char *path;
The system of subdirectories available under GEMDOS is exactly the same
form available under UNIX. This system is now running on systems with
diskette drives, but its advantages become noticeable first when a large mass
storage device such as a hard disk with several megabytes of storage
capacity is connected to the system. After a while, most of the time would
probably be spent looking for files in the directory.
To better organize the data, subdirectories can be placed within
subdirectories. It can therefore become necessary to specify several
subdirectories until one has the directory in which the desired file is stored.
An example might be:
\hugos . dat \cf iles . s\csorts . s\cqsort . s
Translated this would mean: load the file cqsort . s from the subdirectory
csorts . s. This subdirectory c sorts . s is found in the subdirectory
cf iles . s, which in turn is a subdirectory of hugos . dat. If the whole
expression is given as a filename, the desired file will actually be loaded
(assuming that the file and all of the subdirectories are present). If you want
to access another file via the same path (do you understand the term
pathname?), the entire path must be entered again. But you can also make
the subdirectory specified in the path into the current directory, by calling
CHDIR with the specification of the desired path. After this, all of the files
in the selected subdirectory can be accessed just by the filenames. The path
is set by the function.
move.l path,-(sp)
raove.w #$3b,-(sp)
trap #1
addq.l #6,sp
tst.w dO
bne error
Address of the path
Function number
Repair stack
Error occurred?
Apparently
path :
.dc.b ' \hugos .dat\cf iles . s\csorts . s\cqsort . s ' , 0
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$3C CREATE
C: int Fcreate (fname, attr)
char *fname;
int attr;
In all operating systems, the files are accessed through the sequence of
opening the file, accessing the data (reading or writing), and then closing
the file. This "trinity" also exists under GEMDOS, although there is an
exception. Under CP/M, for example, a non-existent file can also be
opened. When a file which does not exist is opened, it is created. Under
GEMDOS, the file must first be created. The call $3C, CREATE, is used
for this purpose. Two parameters are passed to this GEMDOS function: the
address of the desired filename, and an attribute word.
If a zero is passed as the attribute word, a normal file is created, a file which
can be written to as well as read from. If the value 1 is passed as the
attribute the file will only be able to be read after it is closed. This is a type
of software write-protect (which naturally cannot prevent the file from
disappearing if the disk is formatted).
Other possible attributes are $02, $04, and $08. Attribute $02 creates a
"hidden" file and attribute $04 a "hidden" system file. Attribute $08 creates
a file with a "volume label." The volume label is the (optional) name which
a disk can be given when it is formatted. The disk name is then created from
the maximum of 1 1 characters in the name and the extension. Files with one
of the last three attributes are excluded from the normal directory search in
the Desktop. On the ST, however, they appear in the directory, e.g. as
COMMAND.PRG.
When the function CREATE is ended, a file descriptor, also called a file
handle, is returned in DO. All additional accesses to the file take place over
this file handle (a numerical value between 6 and 45). The handle must be
given when reading, writing, or closing files. A total of $28 = 40 files can
be opened at the same time.
If CREATE is called and a file with this name already exists, it is cut off at
zero length. This is equivalent to the sequence delete the old file and create a
new file with the same name, but it goes much faster.
If after calling CREATE you get a handle number back in DO, the file need
not be opened again with $3D OPEN.
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move . w
#$o,-
(sp)
File should have R/W status
pea
filename
Address of the filename on
stack
move . w
#$3c, ■
- (sp)
Fcreate function number
trap
#1
Call GEMDOS
addq . 1
#8 , sp
Clean up stack
tst
dO
Error occurred?
bmi
error
It appears so
move
dO, handle
Save file handle for later
access
filename :
Don't forget the zero
byte
.dc .b
'myf ile
i .dat ' , 0
handle
:
. ds . w
1
$3D OPEN
C: int Fopen (f name, mode)
char *fname;
int mode;
You can only create new files with CREATE, or shorten existing files to
zero length. But you must be able to process existing files further as well.
To do this, such files must be opened with the OPEN function.
The first parameter of the OPEN function is the mode word. With a zero in
the mode word, the opened file can only be read, with one it can only be
written. With a value of 2, the file can be read as well as written. The
filename, ended with a zero byte, is passed as the second parameter.
The OPEN function returns the handle number in DO as the result if the file
is present and the desired access mode is possible. Otherwise DO contains
an error number. See the end of the chapter for a list of the error numbers.
Up until now, when we've discussed file functions, we have referred only
to files. This is only half the story; devices can be opened and closed as well
as files. These devices are the console (keyboard) and monitor, the serial
port and the printer connection. See Chapter 3.1.1 for more information on
GEMDOS and the file/device concept. We want to show you for now how a
device is opened, and what handle to give it. This information is important
insofar as device handles are different from file handles.
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To open a device, the device name is given as a filename. The device names
are: "CON:" for the console, "AUX:" for the serial interface and "PRN:" for
the printer interface. After opening with the appropriate name, you'll get a
word-negative handle. $FFFF(-1) is returned for CON:, $FFFE(-2) is
returned for AUX: and $FFFD(-3) is the handle for the printer port.
move . w
#$2 , - ( sp)
File read and write
pea filename
Address of the filename on the stack
move . w
#$3d, - (sp)
Function number
trap
#1
Call GEMDOS
addq. 1
#8, sp
Clean up the stack
tst . 1
dO
Error occurred?
bmi
error
Apparently
move
dO , f handle
Save file handle for later accesses
filename: Don't forget zero byte!
.dc.b 'myf ile . dat 1 , 0
handle :
.ds.w 1
$3E CLOSE
C: int Fclose (handle)
int handle;
Every opened file should be closed when it is no longer needed within a
program, or when the program itself is ended. Especially when writing,
files must absolutely be closed before the program ends or data may be lost.
Files are closed by the call CLOSE, to which the handle number is passed
as a parameter. The return value will be zero if the file was closed correctly.
Handle number
Function number
Call GEMDOS
Error occurred?
Apparently
handle :
.ds.w 1
move.w handle, -(sp)
move.w #$3e,-(sp)
trap #1
addq.l #4,sp
bmi error
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$3F READ
C: long Fread (handle, count, buff)
int handle;
long count;
char *buf f ;
Opening and closing files is naturally only half of the matter. Data must be
stored and the retrieved later. Reading such files can be done in a very
elegant manner with the function READ. READ expects three parameters:
first the address of a buffer in which the data is to be read, then the number
of bytes to be read from the file, and finally the handle number of the file.
This number you have (hopefully) saved from the previous OPEN.
As return value, DO contains either an error number (hopefully not) or the
number of bytes read without error. No message regarding the end of the
file is returned. This is not necessary, however, since the size of the file is
contained in the directory entiy (see SEARCH FIRST/SEARCH NEXT). If
the file is read past the logical end, no message is given. The reading will be
interrupted at the end of the last occupied allocation unit of the file. The
number of bytes read in this case is always divisible by $400.
pea
buffer
Address of the data buffer
move . 1
#$100, -(sp)
Read 256 bytes
move . w
handle, - (sp)
Space for the handle number
move . w
#$3f , - (sp)
Function number
trap
#1
add. 1
#12, sp
tst . 1
dO
Did an error occur
bmi
error
Apparently
cmp . 1
#$100, dO
256 bytes read?
bne
end_of_f ile
Not enough data in file
handle :
.ds.w 1
Space for the handle number
buffer :
•ds.b $100
Suffices in our example
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$40 WRITE
C: long Fwrite (handle, count, buff)
int handle;
long count;
char *buff;
Writing to a file is just as simple as reading from it. The parameters required
are also the same as those required for reading. The file descriptors from
OPEN and CREATE calls can be used as the handle, but the device
numbers listed for READ can also be used. The output of a program can be
sent to the screen, the printer, or in a file just by changing the handle
number.
pea
buffer
Address of the data buffer
move . 1
#$100,-
- (sp)
Read 256 bytes
move . w
handle
(sp)
Space for the handle
number
move . w
#$40,-
(sp)
WRITE request
trap
#1
add. 1
#12, sp
tst . 1
dO
Did an error occur?
bmi
error
Apparently
handle
. ds . w
1
Space for the handle
number
buffer
;
. ds .b
$100
Suffices in our example
$41 UNLINK
C: int Fdelete (fname)
char * fname;
Files which are no longer needed can be deleted with UNLINK. To do this,
the address of the filename or, if necessary, the complete pathname must be
passed to the function. If the DO register contains a zero after the call, the
file has been deleted. Otherwise DO will contain an error number.
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pea fname
move.w #$41, -(sp)
trap #1
add.l #6,sp
tst.l dO
bmi error
fname :
. dc . b 'b : \hugos . dat\cf iles\csorts\cqsort . s ' , 0
Name of the file to be scratched
Function number FdeleteO
Did an error occur?
Apparently
$42 LSEEK
C: long Fseek (of f set, handle, seekmode)
long offset;
int handle;
int seekmode;
Up to now we have become acquainted only with sequential data accesses.
We can read through any file from the beginning until we come the desired
information. An internal file pointer which points to the next byte to be read
goes along with each read. We can only move this pointer continuously in
the direction of the end of file by reading. A few bytes forward or
backward, setting the pointer as desired, is not something we can do. This
is required for many applications, however.
LSEEK offers an extraordinarily easy-to-use method of setting the file
pointer to any desired byte within the file and to read or write at this
point.This UNIX-compatible option of GEMDOS is much easier to use than
the relative file management methods available under CP/M, for instance.
A total of three parameters are passed to the LSEEK function. The first
parameter specifies the number of bytes by which the pointer should be
moved. An additional parameter is the handle number of the file. The last
parameter is a mode word which describes how the file is to be moved. A
zero as the mode moves the pointer to the start of the file and from there the
given number of bytes toward the end of the file. Only positive values may
be used as the number. With a mode value of 1, the pointer is moved the
desired positive or negative amount from the current position, and a 2 as the
mode value means the distance specified is from the end of the file. Only
negative values are allowed in this mode.
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After the call, DO contains the absolute position of the pointer from the start
of the file, or an error message.
move.w #l,-(sp)
move.w handle, -(sp)
move.l #$-20, -(sp)
move.w #$42, -(sp)
trap #1
add.l #10, sp
tst.w dO
bmi error
Relative from the current file ptr
File handle
32 bytes back
Function number
Did an error occur?
Apparently
handle :
•ds.w 1 Space for the handle number
$43 CHANGE MODE (CHMOD)
C: int Fattrib (fname, flag, attrib)
char *fname;
int flag;
int attrib;
With the CREATE function a file can be assigned a specific attribute. This
attribute can be determined and subsequently changed only with the function
CHANGE MODE. The name of the file must be known because the address
of the name or the complete pathname must be passed to CHMOD. Another
parameter word specifies whether the file attribute is to be read or set.
Moreover, a word must be passed which contains the new attribute. When
reading the attribute of a file this word is not necessary, but should be
passed to the routine as a dummy value. We indicated the possible file
attributes in our discussion of the function CREATE, but here they are again
in a table:
$00 = normal file status, read/write possible
$01 = File is READ ONLY
$02 = "hidden" file
$04 = system file
$08 = file is a volume label, contains disk name
$10 = file is a subdirectory
$20 = file is written and closed correctly
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Attributes $10 and $20 cannot be specified when the file is created. Attribute
$20 is given by the operating system, while the GEMDOS function MKDIR
is used to create a subdirectory. The MKDIR function not only creates the
directory entry with the appropriate attribute, it also physically arranges the
subdirectory on the disk.
After the call, DO will contain the current attribute value, which will be the
new value after setting the attribute, or a negative error number.
First example:
move.w #l,-(sp)
move.w #l,-(sp)
pea pathname
move.w #$43, -(sp)
trap #1
add.l #10, sp
tst.w dO
bmi error
Give file READ ONLY attribute
Set attribute identifier
We also need the pathname
Function number
Did an error occur?
Apparently
pathname :
.dc .b
Don't forget zero byte at end!
' killme .not ' , 0
Second example:
move .w #0, - (sp)
move.w #0,-(sp)
pea pathname
move.w #$43, -(sp)
trap #1
add.l #10, sp
tst.w dO
bmi error
Dummy value, not
Read attribute
and the pathname
Function number
Did an error occu
Apparently
actually required
pathname :
.dc . b
Don't forget zero byte at the end!
' what-am. i ' , 0
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$45 DUP
C: int Fdup (handle)
int handle;
As mentioned in connection with the functions READ and WRITE, the
devices console, line printer and RS-232 are available to the programmer.
This permits input and output to be redirected to these devices. One of the
devices can be assigned a file handle number with the DUP function. After
the call the next free handle number is returned.
move.w STDH, - ( sp)
move . w #$45, - (sp)
trap #1
addq.l #4,sp
tst.l dO
bmi DUPERR
move dO , NSTDH
Parameter is standard handle number (0-5)
Execute DUP
-35,-37 or 0 are possible
Result is non standard handle
number (6-45)
$46 FORCE
C: int Fforce (stdh, nonstdh)
int stdh;
int nonstdh;
The FORCE function allows further manipulation of handle numbers. If in a
program the console input and output are used exclusively via the READ
and WRITE functions with the handle numbers 0 and 1, input or output can
be redirected with a call to this function. Screen outputs are written to a file,
inputs are not taken from the keyboard, but from a previously-opened file.
move.w NSTDil, - ( sp)
move.w STDH, - ( sp)
move.w #$46, -(sp)
trap #1
addq.l #6,sp
tst.l dO
bne FORCE ERR
Parameter is non-standard handle
Standard handle (0-5)
Execute FORCE
-37 or 0 are possible
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$47 GETDIR
C: void Dgetpath (buf , drive)
char *buf;
int drive;
A given subdirectory can be made into the current directory with the
function $37. All file accesses with a pathname then run only in the set
subdirectory. Under certain presumptions it can be possible to determine the
pathname to the current subdirectory. This is accomplished by the function
call GETDIR, $47. This call requires the designation of the desired disk
drive ((^current drive, l=drive A, 2=drive B, etc.) and a pointer to a
64-byte buffer. The complete pathname to the current directory will be
placed in this buffer. The pathname will be terminated by a zero byte. If the
function is called when the main directory is active, no pathname will be
returned. In this case, the first byte in the buffer will contain zero. After the
call, DO must contain the value zero. If the value is negative, an error
occurred, for example if an incorrect drive number was passed.
move.w #0,-(sp) Get pathname of the current drive
pea buffer Address of the 64-byte buffer
move.w #$47,- (sp) Function number
trap #1
addq.l #8,sp
buffer :
.ds.b 128 Better to play it safe
$48 MALLOC
C: long Malloc (number)
long number;
The MALLOC function and the two that follow it, MFREE and
SETBLOCK, are concerned with the memory organization of GEMDOS.
As already mentioned in conjunction with function $31, KEEP PROCESS,
a program is assigned all of the entire memory space available after it is
loaded. This is uncritical in many cases, because only a single program is
running.
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There are applications under GEM in which at least a part of memory is free
from the start of the program, to allow memory to be called for different
GEM functions with M ALLOC. One good example is the item selector box,
which will not appear when no more memory is available.
Other applications are programs which work with overlays, for example. To
load an overlay from the diskette, GEMDOS must have memory available.
For this reason, every program must only have enough memory reserved
for program and data code. The unused memory can then be returned to
GEMDOS by the SETBLOCK command.
If the program needs some of the memory it released, it can request memory
from GEMDOS via the function MALLOC (memory allocate). The number
of bytes required is passed to MALLOC. After the call, DO contains the
starting address of the memory area reserved by the call or an error message
if an attempt is made to reserve more memory than is actually available.
If -1L is passed as the number of bytes to be allocated, the number of bytes
available is returned in DO.
Example 1:
move . 1 #-l,-(sp) Determine number of free bytes
move.w #$48, -(sp) Function number
trap #1
addq.l #6,sp Number of free bytes in DO
Example 2:
move . 1
#$1000, -(sp)
Get hex 1000 bytes
for the program
move . w
#$48, - (sp)
Function number
trap
#1
addq . 1
#6, sp
tst . 1
dO
Error or address of
memory?
bmi
error
Negative long word
= error!
move . 1
dO, mstart
Else start addr of
the reserved area
mstart :
. ds . 1 1
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$49 MFREE
C: long Mfree(addr)
long addr;
An area of memory reserved with MALLOC can be released at any time
with MFREE. To do this, GEMDOS is passed the address of the memory
to be released. The value will usually be the address returned by MALLOC.
If a value of zero is returned in DO, the memory was released by GEMDOS
without error. Negative values indicates errors.
move . 1 instart, - (sp)
move.w #$49, -(sp)
trap #1
addq.l #6,sp
tst.l dO
bne error
Addr of a previously allocated area
Function number
Number of free bytes in DO
Error?
D0O0 is error!
mstart :
. ds . 1 1
$4A SETBLOCK
C: int Mshrink (dummy, block, newsize)
word dummy = 0;
long block;
long newsize;
In contrast to the MALLOC function, a specific area of memory can be
reserved with the function SETBLOCK. The memory beginning at the
specified address is returned to GEMDOS, even if it was reserved before.
This function can be used to reserve the actual memory requirements of a
program and release the remaining memory.
The parameters the function requires are the starting address and the length
of the area to be reserved. The area specified with these parameters is then
reserved by GEMDOS and is not released again until the end of the program
or after calling the MFREE function.
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Usually programs will begin with the following command sequence or
something similar. After the call, DO must contain zero, otherwise an error
occurs.
move . 1
a7, a5
Save stack pointer in A5
move . 1
#ustck, a7
Set up stack for the program
move . 1
4 (a5) , a5
A5 now points to the base-page start
exactly $100 bytes below the prg start
move . 1
$c (a5) , dO
$C(A5) contains length of the prg area
add. 1
$14 (a5) , dO
$14 (A5) containing the length of the
initialized data area
add. 1
$lC(a5) , dO
$1C(A5) contains length of the
uninitialized data area
add. 1
#$100, dO
Reserve $100 bytes base page
move . 1
dO,- (sp)
DO contains the length of the area
to be reserved
move . 1
a5,- (sp)
A5 contains the start of the area
to be reserved
move . w
#0,- (sp)
Meaningless word, but still necessary!
move . w
trap
#$4a, - (sp)
#1
Function number
add. 1
#12, sp
Clean up the stack as usual
tst . 1
dO
Did an error occur?
bne
error
Stop
Here the program continues...
$4B EXEC
C: long Pexec (mode, ptrl, ptr2, ptr3)
int mode ;
char *ptrl;
char *ptr2;
char *ptr3;
The PexecQ function permits loading and chaining programs. If desired, the
program loaded can be automatically started. In addition to the function
number, the addresses of three strings and a mode word are expected on the
stack.
Let's talk a bit about the mode word. This word has a value of 0, 3, 4 or 5.
k
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Mode=0 represents the LOAD'N'GO option: In this case, the file is loaded
from diskette and the filename and pathname are received in PTR1. PTR2
contains the option of the command tail, comparable to choosing .TTP in a
dialog box. PTR2 stands for the environment string, which apparently has
no function under GEMDOS. If the command tail and the environment
string aren't used, then there is a null-byte at this point.
After loading the program, the system automatically starts the program. The
called program, started by the Pexec() call, remains in memory. Eventually
opened files will pass on the most recently started program. This new
program will be classified as a "child process." Once the child process is
done, control returns to the original program, or "parent process."
If the mode word is a three, the parameters PTR1 to PTR3 are handled in
the same form as when mode = 0, except that the program will not be
executed once it is loaded into memory. After calling Pexec() with mode =
3, the address of the basepage of the loaded program is found in DO.
At first glance this may not make sense, but this function is the minimum
that any good debugger should have. When you want to search a program
for errors with a debugger, you would want control to go to the debugger,
instead of the program loading and immediately executing. If the program
ran without the debugger, and it had errors, it would crash. The LOAD
option of Pexec() offers help.
If the mode word = 4, the program found in memory will be started. PTR1
waits for the address of the necessary basepage. PTR2 and PTR3 are
unused. This way you can start a program previously loaded with Pexec(),
mode = 3.
The last option is a mode word of 5. This option sets up the basepage in
memory, as well as allocating the largest free block of memory. Naturally,
no more data can go into the basepage after this call, especially text, data
and BSS ranges. These must be provided for by the programmer.
pea
env
pea
com
pea
fil
move . w
#0, - (sp)
move . w
#$4b, - (sp)
trap
#1
add. 1
#16, sp
Environment
Command line
Filename
Load and start.
Function number
Here we come to
chained program
please
the end of the
or loaded module
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fil:
Load sort routine
• dc .b
'qsort .prg' , 0
com:
Sort the file in ascending order
.dc .b
'up data.asc’,0
env :
No environment
. dc . w
0
$4C TERM
C: void Pterm (retcode)
int retcode;
TERM $4C represents the third method, after PtermO(), function number
$00, and Ptermres(), function number $31, of ending a program. Pterm()
automatically makes the memory used by the program available to
GEMDOS again. Unlike TERM $00, however, a programmer-defined value
other than zero can be returned to the caller. This allows a short message to
be passed back to the calling program.
All files opened in this process will be automatically closed from PTERM.
move.w #37, -(sp) Any 2-byte value
move.w #$4c,-(sp) End program
trap #1 . . .now
• We never get here
$ 4E SFIRST
C: int Fsfirst (fnam, attr)
char *fnam;
int attr;
The SFIRST function can be used to check to see if a file with the given
name is present in the directory. If a file with the same name is found, the
filename, the file attribute, data and time of creation, and the size of the file
in bytes is returned. This information is placed in the DTA buffer, whose
address is set with the SETDTA function, by GEMDOS.
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One feature of this function is that the filename need not be specified in its
entirety. Individual characters in the filename can be exchanged for a
question mark and entire groups of letters can also be replaced by a
In the extreme form a filename would be reduced to the string In
this case the first file in the directory would satisfy the conditions and the
filename would appear in the DTA buffer along with the other information.
In addition to the filename, the SFIRST function must also be given a
search attribute. The possible parameters of the search attribute correspond
to the attributes which can be specified in CHMOD function:
$00 = Normal access, read/write possible
$01 = Normal access, write protected
$02 = Hidden entry (ignored by the ST desktop)
$04 = Hidden system file (ignored like $02)
$08 = Volume label, diskette name
$10 = Subdirectory
$20 = File will be written and closed
The following rules apply when searching for files:
• If the attribute word is zero, only normal files are recognized.
System files or subdirectories are not recognized.
• System files, hidden files, and subdirectories are found when
the corresponding attribute bits are set. Volume labels are not
recognized, however.
• In order to get the volume label, this option must be expressly
set in the attribute word. All other files are then ignored.
• After the call, DO contains zero if the desired file has been
found. The 44-byte DTA buffer is then constructed as follows:
Bytes
0-20
Byte
21
Bytes
22-23
Bytes
24-25
Bytes
26-29
Bytes
30-43
Reserved for GEMDOS
File attribute
Clock time of file creation
Date of file creation
File size in bytes (long)
Name and extension of the file
If, however, no file is found which corresponds to the specified search
string, the error message -33, file not found, is returned.
pea dta
move.w #la,-(sp)
Set up DTA buffer
Function number SETDTA
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trap #1
addq.l #6,SP
move . w #attrib, - (sp)
move.l ffilnam, - (sp)
move . w #$4e,-(sp)
trap #1
addq.l #8,sp
tst dO
bne notfound
Attribute value
Name of file to search for
Function number
File found?
Apparently not
attrib :
. dc . b 0
f ilnam:
. dc . b
Search for normal files only
0 Search for the 1st possible file
dta :
. ds . b 44
Space for the DTA buffer
$4F SNEXT
C: int FsnextO
The SNEXT function (Search next) can be used to see if there are other files
on the disk which match the filename given. To do this, only the function
number need be passed; SNEXT does not require any parameters. All of the
parameters are set from the SFIRST call.
If the search string is very global, as in the previous example, all of the files
on a diskette can be determined and displayed one after the other with
SFIRST and SNEXT. This makes it rather easy to display a directory
within a program. The SNEXT function is called repeatedly and the
contents of DO are check afterwards. If DO contains a value other than zero,
either an error occurred, or all of the directory entries have been searched.
move.w #$4f , - (sp)
trap #1
addq.l #2,sp
tst.l dO
Search next
Is it still there?
No more by negative values
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$56 RENAME
C: int F rename (dummy, oldname, newname)
int dummy = 0 ;
char*oldname;
char *newname;
Files are renamed under GEMDOS with the RENAME function, which
requires two pointers to file or pathnames. The first pointer points to the
new name, with the specification of the pathname if necessary; the second
pointer points to the previous name. A 2-byte parameter is required in
addition to the two pointers. We were unable to determine the function of
the additional word parameter. Different values had no (recognizable) effect.
As a return value, DO contains either zero, meaning that the name was
changed correctly, or an error code.
pea
newnam
New filename
pea
oldname
File to rename
move . w
#0 , - (sp)
Dummy
move . w
#$56, -(sp) Function number
trap
#1
add. 1
#12, sp
tst . 1
dO
Test for error
oldnam
Don't forget zero byte at end
.dc.b '
oldf ile .dat ' , 0
newnam
.dc.b '
newname . dat ' , 0
$57 GSDTOF
C: void Fdatime (timeptr, handle, flag)
int handle;
char * timeptr;
int flag;
If the directory is displayed as text rather than icons on the desktop, the date
and time of file creation as well as the size of the file in bytes is shown. The
time and date can either be set or read with function $57. To do this it is
necessary that the file be already opened by OPEN or CREATE. The handle
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number obtained at the opening must be passed to the function. Additional
parameters are a word which acts as a flag as to whether the time and date
are to be set (0) or read (1), and a pointer to a 4-byte buffer which either
contains the result or will be provided with the required data before the call.
This date buffer contains the time in the first two byes and the date in the
last two bytes. The data format is identical to that of the functions for
setting/reading the time and date.
A word of warning about this section. Programmers who call this function
in C and assembler must make allowances. In the include file OSBIND.H,
the parameters 'timeprt' and 'handle' are exchanged. A C call must follow
this scheme when using the abovementioned include file. In assembler
programs, however, the normal sequence of parameters must be followed.
Example 1:
move . w
pea
move . w
move . w
trap
add. 1
handle :
buff :
#1, - (sp)
buff
♦handle, - (sp)
#$57, - (sp)
#1
#10, sp
Read time and date
4 byte buffer
File must first be opened
Function number
.ds .b
2
.ds .b
4
Example 2:
move . w
#0, - (sp)
pea
buff
move . w
♦handle, - (sp)
move . w
#$57, - (sp)
trap
#1
add. 1
#10 , sp
handle :
. ds . b 2
buff:
. ds . b 4
Set time and date
4 byte buffer
File must first be opened
Function number
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3.1.1 Memory, files and processes
Will it never end? You just mastered getting around the operating system of
your C-64, Atari 800 or other 8 -bit machine, then suddenly you're
confronted with new things such as memory management, handles, and
even parent/child processes. Other computers don't have these knickknacks.
Is it really that important to have them? Doesn't the computer run fine
without them? And then there are these types that don't stay at the memory
address you want them to operate. It was so much simpler in the past.
Those were the days when you knew where a program loaded and ran, and
when you assembled things at the necessary addresses.
I/O conversion, Malloc, basepage, Pexec or Dup are such obscure terms.
Yes, eveiything was a lot simpler in the good old days.
We're here to help you overcome the "culture shock" that hits most 8-bit
owners when they get a 16-bit computer. In order to ease you into the most
effective use of the Atari ST operating system, we want to show you what
special functions like MALLOC, SETBLOCK, TERM and PEXEC are, as
well as the use and design of the basepage. We'll close with DUP and
FORCE, the input/output division.
The concept of memory processing
When the ST is first turned on, it goes through a normal boot sequence.
This sequence happens regardless of the ROMs or operating system in your
ST. The system boots, then displays the Desktop on the monitor.
Up to this time there have already been a number of procedures done within
the ST. So other memory, peripheral chips and operating system routines
are initialized, and the programs in the Auto folder executed.
The Desktop itself is an independent program, the same as an editor,
BASIC interpreter or compiler. Whether it is in ROM or on the TOS.IMG
disk, it starts like a program loaded from disk. One specific task of the
Desktop is to load other programs and give computer control to these
programs. As we said earlier, we'll take a closer look.
The function call Pexec is used by the Desktop in loading programs. When
you choose a program with the mouse, a corresponding Pexec call with the
filename and parameters given in the dialog box is executed. GEMDOS
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takes control from the call and looks for free memory. But what’s "free
memory"? Every program has its memory range; free memory is
unoccupied memory, into which a program can be loaded. The start of free
memory (TP A) will then have a basepage added to it. This basepage is 256
bytes ($100 bytes) in size, and contains special information about the
program being loaded. The basepage’s design looks like this:
Offset
Identifier
Funct ion
0x00
p_lowtpa
Pointer to start of basepage
0x04
p_hitpa
Pointer to the end of free memory
0x08
p tbase
Pointer to beginning of program (text segment
0x0c
p tlen
Program size (Text segment)
0x10
p_dbase
Pointer to start of data segment
0x14
p_dlen
Data segment size
0x18
p_bbase
Pointer to beginning of BSS segments
Oxlc
p_ien
BSS segment size
0x20
p_dta
Pointer to DTA buffer
0x24
p_parent
Pointer to parent's basepage
0x28
(reserved)
0x2c
p_env
Pointer to environment string
0x80
cmdlin
Command line
The range between 0x30 and 0x7f is used by the operating system. You
should not use this range.
Although the basepage is sent from the system, there aren’t many other
things that need to be done. First, after the program is loaded directly
behind the basepage, the data is made available and put into the appropriate
areas.
The program is relocated after loading (if needed). The programmer as a
rule has no control over the memory where the program resides, since
Pexec controls the free memory, and loads the program into that memory.
The classic 8 -bit computer must load a program into a specific range of
memory, which easily allows combining multiple programs into one
memory register. These combinations should be avoided at all costs under
"proper" GEMDOS programming. Instead, assemble the program, putting
relevant addresses into a loader that Pexec will load first, then act upon
these addresses before loading the main program.
The program will start after this work. It is now a child of a program that it
has called. The calling program will be identified as a parent. This parent
has no gender; the general reference of parent and child solves any linguistic
problems.
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For the moment, let's concentrate on the child. This process has from the
first set up the entire free memory needed. The first action should be to
determine the amount of memory needed in any program, and hand the rest
over to GEMDOS. And how do you allocate memory? Once you know it,
it's simple to follow.
After the start of the program, you'll find the address of the basepage on the
stack. All the program data and calculations for memory requirements is in
the basepage. These data are p_tlen, p_dlen and p_blen. Add these values
together, and there you have your range needed by the program. In
addition, you have to reserve memory for die stack, which lies in protected
memory.
When you analyze the beginning of a program with a disassembler, you'll
frequendy find die following or a similar sequence:
move .1 a7 , a5
move.l 4 (a5) , a5
move . 1 $c(a5) ,d0
add . 1 $14 (a5) , dO
add. 1 $lc (a5) , dO
add. 1 #$500, dO
move.l d0,dl
add.l a5,dl
and . 1 #-2,dl
move.l dl,a7
move.l d0,-(sp)
move.l a5,-(sp)
clr.w -(sp)
move.w #$4a,-(sp)
trap #1
add .1 #12 , sp
store stack to determine basepage
base page is now in a5
text segment length stands in dO
add to that the length of the data- and
the bss segments
and to that add the amount needed for the stack
length + address of basepage
be sure that the stack starts at an even address
now put the stack where you want it
size of reserved area
from where you want it reserved (base page)
dummy
setblock-function number
call gemdos
and clear off the stack
This program section takes up all tasks which were demanded from
GEMDOS. After GEMDOS has reduced the amount of available memory
accordingly, the program can then continue.
What is released memory? This is done by GEMDOS for further Pexec
calls. The child process has no access authority. You should ideally be able
to use memory without further measurements. When you keep putting data
into this range, the data could occasionally become "overstuffed". Different
functions of GEMDOS, the VDI and AES are reserved by Malloc, and
putting data into the received range. When you haven't protected your data,
the chances are good that you'll lose your data.
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When you have not set up available memory, then you can call Malloc from
the operating system. After the call, you get the starting address of the
reserved range. This range is "safe"— you can’t put any other process into
this range. When the memory is no longer free, the best thing to do is call
Mfree. Then you can choose from another process.
When you hold to these conventions, then one can’t get past. The memory
is again protected, and you can load in any other programs. Every new
loading makes up another child of the parent program. So overlaying
programs is only allowed when the available memory is protected.
If a program ends with PtermO or Pterm, then the designated memory is
released from the program. Additional memory reserved by Malloc will be
released. Also, any open files will be closed. Then control returns to the
parent, whereas it was previously held by the child.
Handles, files, devices
The basic file handling functions in GEMDOS are quite simple. Fopen or
Fcreate open a file; this file is read from with Fread, and written to with
F write. Fclose closes the file. All file accesses run under a number, initially
stated in Fopen or Fcreate. This number between 6 and 45 is called a "non
standard handle." Non standard handles are used only in conjunction with
files.
It is logical to assume that there are also "standard handles." And so there
are; these are the handles between 0 and 5. These handles can be organized
as either a file or as a "character device." Character devices in the ST consist
of the keyboard, the monitor, the printer interface and the serial interface.
Here is the normal assignment for these standard handles:
Handle Device
0 Console input (Stdin)
1 Console output (Stout)
2 Serial interface (AUX)
3 Printer interface (PRN)
The standard handles 4 and 5 aren’t used in ST GEMDOS as a rule. The
"correct" GEMDOS layout sees handle 2 as a standard error device (Stderr).
These will shift AUX and PRN over one place. Handle 5 is originally used
as a null-device. This null-device can store output in an empty space. This
setup is unfortunately not implemented in the ST.
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That's not all. There are also character handles which are assigned in
connection with the character devices. These character handles are received
only after an Fopen or Fcreate, and give the names of the desired character
devices. The names of the character devices are "CON:", "AUX:" and
"PRN:".
Standard handles serve two distinct purposes. The first is that you can use
them for Fopen or Fcreate without actually having Fopen or Fcreate. These
handles will perform any process arranged by the parent process. The
second purpose is the allowance for altering standard handles.
For example: You work on a program which waits for a quantity of data
from the keyboard; this data is processed, saved to disk, and the results sent
to a printer. Now, you could do every test run by hand, and end up with a
pile of paper, until the program runs free of error. However, you could just
as easily pass along the keyboard input and the printer output by writing all
the keyboard input into a file, and having the file data do the typing. You
could also have the printer output sent to a File instead of the printer, so you
could save yourself a waste of paper, and still see the result later.
These conversions use both standard and non standard handles, controlled
by the Force function. Here is a program fragment which contains the
necessary calls for using a file to send "keyboard" input from a file:
move . w
#0 , - ( sp)
"read only" mode
pea
fil_nam
name of the input file
move . w
#$3d, - ( sp)
fopen ( )
trap
#1
gemdos call
addq . 1
#8, sp
tst . 1
dO
did fopen work?
bmi
opn err
negative long is an error
move . w
dO , f handle
the handle we need is our
move . w
dO, - (sp)
our non std handle
move . w
#0, - (sp)
std handle console
move . w
#$46, -(sp)
force ( )
trap
#1
call gemdos
addq . 1
#6, sp
tst . 1
dO
read error
bmi
frc err
. input starts from
. file here
After this call (and this is extremely important), every GEMDOS call for a
character from the keyboard will get it from the file. The keyboard must not
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be read with Fread(). Cconin(), Crawio(), Cconrs() and the other functions
dealing with keyboard data also look to the file data instead of the keyboard.
The use of character functions (Conin, etc.) in connection with this are
problematical. These functions have no options in working with the called
program when the file ends. This information can be had only by using the
Fread() function.
An exception is when you mark the input file with a special end-of-file
(EOF) indicator. One character frequently used for this purpose is
<ControlxZ>, with an ASCII value of 26 or Ox la. When you reserve this
character for an EOF character, then you can read this character in addition
to the standard arrangement of 0. For particularly elegant programming, you
can follow it with the Fdup function. Here's a short example:
move . w
#0, - ( sp)
our std handle
move . w
#$45, - (sp)
dup ( )
trap
#1
call gemdos
addq . 1
#4 , sp
tst . 1
dO
was there still a non std handle free?
bmi
no_more
evidently not
move . w
dO, dup_han
make a note of it!
here the key/file transfer program can follow
Here is the program itself. Now you can only start with keyboard
input
move . w
move . w
move . w
trap
addq . 1
tst . 1
bmi
dup_han, - (sp)
#0, - ( sp)
#$46, - (sp)
#1
#6, sp
dO
our non std handle from dup ( )
there should be a std handle
force ( )
call gemdos
read error
frc err
from this point on, the input is again
handed over to the keyboard
First, the handle from Stdin, the 0, is duplicated by the Dup function. The
keyboard is accessed by the standard handle as well as the non standard
handle, (only with Fread, naturally). The input routine then switches over to
the file, giving the effect described above. All characters that you would
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normally send over the keyboard are read from the file. When the input is
ended, then the duplicated handle is returned to keyboard input with a Force
call. The still open file should be closed by an Fclose call.
From reading the above, it should be clear to you the way that the printer
output works. Again, open a file with Fcreate(). The handle used can be
Forced from the printer. Then all data that would normally go to the printer
will be sent to a file.
A further application would be when you move output from the screen to
the printer. This can also be easily realized.
GEMDOS error codes and their meaning
The GEMDOS functions return a value giving information about whether or
not an error occurred during the execution of the function. A value of zero
means no error; negative values have the following meanings:
-32 Invalid function number
-33 File not found
-34 Pathname not found
-35 Too many files open (no more handles left)
-36 Access not possible
-37 Invalid handle number
-39 Not enough memory
-40 Invalid memory block address
-46 Invalid drive specification
-49 No more files
In addition to these error messages, the BIOS error messages may occur.
These error messages have numbers -1 to -31 and are described in section
3.3
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3.2 The BIOS Functions
The software interface between GEMDOS and the hardware of the computer
is the BIOS (Basic Input Output System). The BIOS, as the name suggests,
is concerned with the fundamental input/output functions. This includes
screen output, keyboard input, printer output, RS-232 functions and, of
course, disk input and output.
The BIOS functions are also available to user programs. The trap
instruction of the 68000 processor is used to call them. Any data required is
passed through the stack and the result of the function is returned in the DO
register. The machine language programmer should be aware that the
contents of D0-D2 and A0-A2 are changed when calling BIOS functions;
the remaining registers remain unchanged.
BIOS function calls are even simpler if you program in C. Here you can use
simple function calls with the corresponding parameter lists. The function
calls are stored as macros in an include file. In the examples, the definition
of the function and its parameters in C will be shown. For assembly
language programmers, the use is described in an example.
TRAP # 1 3 is reserved for the BIOS functions.
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n
0 Getmpb
get memory parameter block
C: void Getmpb (pointer)
long pointer;
Assembler:
move . 1 pointer, - (SP)
move.w #0,-(SP)
trap #13
addq.l #6,sp
This function fills a 12-byte block whose address is contained in pointer
with the memory parameter block. This block contains three pointers:
long md_mfl
long md__mal
long md_rover
Memory free list
Memory allocated list
Roving pointer
The structures to which each pointer points are constructed as follows:
long
md link
Pointer to next block
long
md start
Start address of the block
long
md length
Length of the block in bytes
long
md own
Process descriptor
Example:
move . 1
#buf fer, - (sp)
Buffer for MPB
move . w
#0, - (sp)
getmpb
trap
#13
Call BIOS
addq . 1
#6, sp
Stack correction
We get the values $48E, 0, and $48E. The following data are at address
$48E (for 1MB RAM):
m_link 0
m_start $3B900
m_length $3C700
m own 0
No additional block
Start address of the free memory
Length of the free memory
No process descriptor
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1 Bconstat return input device status
C: int Bconstat (dev)
int dev;
Assembler:
move.w dev,-(sp)
move.w # 1 , — ( sp)
trap #13
addq.l #4,sp
This function returns the status of an input device, defined as follows:
Status 0 No characters ready
Status -1 (at least) one character ready
The parameter dev specifies the input device:
dev Input device
0 PRT : , Centronics interface
1 AUX:, RS-232 interface
2 CON:, Keyboard and screen
3 MIDI, MIDI interface
4 IKBD, Keyboard port
The following table lists the allowed accesses to these devices:
Operation
PRT:
AUX:
CON:
MIDI
IKBD
Input status
no
yes
yes
yes
no
Input
yes
yes
yes
yes
no
Output status
yes
yes
yes
yes
yes
Output
yes
yes
yes
yes
yes
This example waits until a character from the RS-232 interface is ready.
wait move.w #l,-(sp)
move.w # 1 , — ( sp )
trap #13
addq.l #4,sp
tst dO
beq wait
RS-232
bconstat
character available?
no, wait
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2 Bconin read, character from device
C: long Bconin (dev)
int dev;
Assembler:
move.w dev,-(sp)
move.w #2,-(sp)
trap #13
addq.l #4,sp
This function fetches a character from an input device. The parameter dev
has the same meaning as in the previous function. The function returns
when a character is ready.
The character received is in the lowest byte of the result. If the input device
was the keyboard (con, 2), the key scan code is also returned in the lower
byte of the upper word (see the description of the keyboard processor).
Example:
move.w #2, - (sp) con
move.w #2,-(sp) bconin
trap #13
addq.l #4,sp
3 B con Out write character to device
C: void Bconout (dev, c)
int dev, c;
Assembler:
move.w c,-(sp)
move.w dev,-(sp)
move.w #3,-(sp)
trap #13
addq.l #6,sp
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This function serves to output a character "c" to the output device dev
(meaning is the same as for the previous function). The function returns
when the character has been outputted.
Example:
move.w #'A',-(sp)
move.w #0,-(sp)
move.w #3,-(sp)
trap #13
addq.l #6,sp
The example outputs the letter "A" to the printer.
PRT :
Bconout
4 RwabS read and write disk sector
C: long Rwabs (rwf lag, buffer, number, recno,dev)
long buffer;
int rwflag, number, recno, dev;
Assembler:
move.w dev,-(sp)
move.w recno, -(sp)
move.w number, -(sp)
move . 1 buffer, -(sp)
move.w rwflag, -(sp)
move.w #4,-(sp)
trap #13
add.l #14, sp
This function serves to read and write sectors on the disk. The parameters
have the following meanings:
rwflag Meaning
0 Read sector
1 Write sector
2 Read sector, ignore disk change
3 Write sector, ignore disk change
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The parameter buffer is the address of a buffer into which the data will be
read from the disk or from which the data will be written to the disk. The
buffer should begin at an even address, or the transfer will run very slowly.
The parameter number specifies how many sectors should be read or written
during the call. The parameter recno specifies which logical sector the
process will start with.
The parameter dev determines which disk drive will be used:
dev Drive
0 Drive A
1 Drive B
2+ Hard disk, RAM disk, network
The function returns an error code as the result. If this value is zero, the
operation was performed without error. The returned value will be negative
if an error occurred (please see the Floprd entry of the XBIOS listing for
error codes and their meanings).
Example:
move . w
#0, - (sp)
Drive A
move . w
#10, -(sp)
Start at logical sector 10
move . w
#2, - (sp)
Read 2 sectors
move . 1
♦buffer, - (sp)
Buffer address
move . w
#0, - (sp)
Read sectors
move . w
#4, - (sp)
rwabs
trap
#13
add. 1
#14, sp
:fer
ds.b 2*512
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5 Setexec
set exception vectors
C: long Setexec (number, vector)
int number;
long vector;
Assembler:
move . 1 vector, -(sp)
move.w number,- (sp)
move.w #5,-(sp)
trap #13
addq.l #8,sp
The function setexec allows one of the exception vectors of the 68000
processor to be changed. The number of the vector must be passed in
number and the address of the routine pertaining to it in vector. The
function returns the old vector as the result. If you just want to read the
vector, pass the value -1 as the new address. The 256 processor vectors as
well as 8 vectors for GEM, which numbers $100 to $107 (address $400 to
$4 1C) can be changed with this function.
Example:
move . 1 #buserror, - (sp)
move.w #2,-(sp)
move.w #5,-(sp)
trap #13
addq.l #8,sp
buserror
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6 Tickcal return millisecond per tick
C: long Tickcal ()
Assembler:
move.w #6,-(sp)
trap #13
addq.l #2,sp
This function returns the number of milliseconds between two system timer
calls.
Example:
move.w #6,-(sp)
trap #13
addq.l #2,sp
Result: 20 ms
7 Getbpb get BIOS parameter block
C: long Getbpb (dev)
int dev;
Assembler:
move.w dev,-(sp)
move.w #7,-(sp)
trap #13
addq.l #4,sp
This function returns a pointer to the BIOS Parameter Block of the drive
dev (0=drive A, l=drive B).
The BPB (BIOS Parameter Block ) is constructed as follows:
int
recsiz
Sector
size
in bytes
int
clsiz
Cluster
size
in sectors
int
clsizb
Cluster
size
in bytes
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int
rdlen
Directory length in
sectors
int
f siz
FAT size in sectors
int
f atrec
Sector number of the
second FAT
int
datrec
Sector number of the
first data cluster
int
numcl
Number of data clusters on the disk
int
bf lags
Misc. flags
The function returns the address $3E3E for drive A and the address $3E5E
for drive B. An address of zero indicates an error.
Example:
move.w #0,-(sp)
move . w #7, - (sp)
trap #13
addq.l #4,sp
Here are the BPB data for 80 track single and double-sided disk drives:
Drive A
getbpb
Parameter
80 track SS
80 track
recsiz
512
512
clsiz
2
2
clsizb
1024
1024
rdlen
7
7
f siz
5
5
f atrec
6
6
datrec
18
18
numcl
351
711
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8 Bcostat return output device status
C: long Bcostat (dev)
int dev;
Assembler:
move.w dev,-(sp)
move.w #8,-(sp)
trap #13
addq.l #4,sp
This function tests to see if the output device specified by dev is ready to
output the next character, dev can accept the values which are described in
function one. The result of this function is either - 1 if the output device is
ready, or zero if it must wait.
Example:
move.w #0/-(sp) Printer ready?
move.w #8,-(sp) bcostat
trap #13
addq.l #4,sp
9 Mediach inquire media change
C: long Mediach (dev)
int dev;
Assembler:
move.w dev,-(sp)
move.w #9,-(sp)
trap #13
addq.l #4,sp
This function determines if the disk has been changed. The parameter dev,
the drive number (0=drive A, l=drive B), must be passed to the routine.
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One of three values can occur as the result:
0 Diskette was
1 Diskette may
2 Diskette was
definitely not changed
have been changed
definitely changed
Example:
move.w #l,-(sp)
move.w #9,-(sp)
trap #13
addq .1 # 4 , sp
Drive B
mediach
10 Drvmap
inquire drive status
C: long Drvmap ()
Assembler:
move.w #10, - (sp)
trap #13
addq.l #2,sp
This function returns a bit vector which contains the connected drives. The
bit number n is set if drive n is available (0 means A, etc.). Even if only one
drive is connected, %11 is still returned, since two logical drives are
assumed.
Example:
move.w #10, -(sp)
trap #13
addq.l #2,sp
drvmap
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11 Kbshift inquire/ change keyboard status
C: long Kbshift (mode)
int mode;
Assembler:
move.w mode,-(sp)
mode.w #11, -(sp)
trap #13
addq.l #4,sp
With this function you can change or determine the status of the special keys
on the keyboard. If mode is -1, you get the status, a positive value will be
accepted as the status. The status is a bit vector constructed as follows:
Bit Meaning
0 Right shift key
1 Left shift key
2 Control key
3 ALT key
4 Caps Lock on
5 Right mouse button (CLR/HOME)
6 Left mouse button (INSERT)
7 Unused
Example:
move.w #-l,-(sp) Read shift status
move.w #11, -(sp) kbshift
trap #13
addq.l #4,sp
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3.3 The XBIOS
To support the special hardware features of the Atari ST, there are extended
BIOS (XBIOS) functions, which are called by a trap# 14 instruction.
These functions, like the normal BIOS functions, can be called from
assembly language as well as from C. When calling from C, a small TRAP
handler in machine language is again necessary, which is contained in
OSBIND and can look like this:
trapl4 :
move . 1
(sp) +, retsave
Save
return address
trap
#14
Call
XBIOS
move . 1
retsave, - (sp)
Restore return address
rts
• bss
retsave ds . 1 1 Space for the return address
Macro functions can be used in C which allow the extended BIOS functions
(extended BIOS, XBIOS) to be called by name. The appropriate function
number and TRAP call will be created when the macro is expanded.
When working in assembly language, the function number of the XBIOS
routine need simply be passed on the stack. The XBIOS has 40 different
functions whose significance and use are described on the following pages.
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0 Initmous initialize mouse
C: void Initmous (type, parameter, vector)
int type ;
long parameter, vector;
Assembler:
move.l vector, -(sp)
move . 1 parameter, - (sp)
move.w type,-(sp)
move . w #0 , (-sp)
trap #14
add.l #12, sp
This XBIOS function initializes the routines for mouse processing. The
parameter vector is the address of a routine which will be executed
following a mouse-report from the keyboard processor. The parameter type
selects from among the following alternatives:
type
0 Disable mouse
1 Enable mouse, relative mode
2 Enable mouse, absolute mode
3 unused
4 Enable mouse, keyboard mode
This allows you to select if mouse movements are to be reported and in
what manner this will occur.
The parameter parameter points to a parameter block, which is constructed
as follows:
char topmode
char buttons
char xparam
char yparam
The parameter topmode determines the layout of the coordinate system. A 0
means that Y=0 lies in the lower comer, 1 means that Y=0 lies in the upper
comer.
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The parameter buttons is a parameter for the command "set mouse
buttons" of the keyboard processor (see description of the IKBD, intelligent
keyboard).
The parameters xparam and yparam are scaling factors for the mouse
movement. If you have selected 2 as the type, the absolute mode, the
parameter block determines four more parameters:
int xmax
int ymax
int xstart
int ystart
These are the X- and Y-coordinates of the maximum value which the mouse
position can assume, as well as the start value to which the mouse will be
set.
Example:
move.l Ivector, - (sp)
move.l #parameter, - (sp)
move.w #1 , - ( sp)
move . w #0, - (sp)
trap #14
add. 1 #12, sp
Address of the mouse position
Address of the parameter block
Enable relative mouse mode
Init mouse
parameter dc.b
vector
Mouse interrupt routine
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1
1 Ssbrk save memory space
C: long Ssbrk (number)
int number;
Assembler:
move.w number, -(sp)
move.w #l,-(sp)
trap #14
addq.l #4,sp
This function reserves memory space. The number of bytes must be passed
in number. Space is prepared at the upper end of memory. The function
returns the address of the reserved memory area as the result. This function
must be called before initializing the operating system, meaning that it must
be called from the boot ROM, before the operating system is loaded.
Example:
move.w #$400, -(sp)
move.w #l,-(sp)
trap #14
addq.l #4,sp
Reserve IK
ssbrk
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2 Physbase return screen RAM base address
C: long Physbase ()
Assembler:
move #2,-(sp)
trap #14
addq.l #2,sp
This function returns the base of the physical screen RAM. The physical
screen RAM is the area of memory displayed by the video shifter. The result
is a long word.
Example:
$F8000, base address of the screen for 1 MB RAM
$78000, base address of the screen for 512 KB RAM
3 Logbase set logical screen base
C : long Logbase ()
Assembler:
move #3, - (sp)
trap #14
addq.l #2,sp
The logical screen base is the address which is used for all output functions
as the screen base. If the physical and logical screen bases are different, one
screen will be displayed while another picture is being constructed in a
different area of RAM, which will be displayed later. The result of this
function call is again a longword.
Example:
$F8000, base address of the screen for 1 MB RAM
$78000, base address of the screen for 512 KB RAM
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4 Getrez return screen resolution
C: int Getrez ()
Assembler:
move.w #4,-(sp)
trap #14
addq .1 #2 , sp
This function call returns the screen resolution:
0 := Low resolution, 320*200 pixels, 16 colors
1 := Medium resolution, 640*200 pixels, 4 colors
2 := High resolution, 640*400, pixels, monochrome
Example:
2, monochrome
5 Setscreen set screen parameters
C: void Setscreen (logadr, physadr, res)
long logadr, physadr;
int res;
Assembler:
move.w res,-(sp)
move.l physadr, - (sp)
move . 1 logadr, -(sp)
move.w #5,-(sp)
trap #14
add.l #12, sp
This function changes the screen parameters which can be read with the
previous three functions. If a parameter should not be set, a negative value
must be passed. The parameters are set in the next VBL routine so that no
disturbances appear on the screen.
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Example:
move.w #— 1, - (sp)
move . 1 #$70000, - (sp)
move . 1 #$70000, - (sp)
move.w #5, - (sp)
trap #14
add.l #12, sp
Set the physical and the logical screen address to $70000, retain the
resolution.
6 Setpalette set color palette
C: void Setpalette (paletteptr)
long paletteptr;
Assembler:
move.l paletteptr, - (sp)
move.w #6, - (sp)
trap #14
addq.l #6,sp
A new color palette can be loaded with this function. The parameter
paletteptr must be a pointer to a table with 16 colors (each a word). The
address of the table must be even. The colors will be loaded at the start of
the next VBL.
Example:
move.l #palette, - (sp)
move.w #6, - (sp)
trap #14
addq .1 # 6 , sp
palette dc.w $777, $700, $070, $007, $111, $222, $333, $444
dc.w $555, $000, $001, $010, $100, $200, $020, $002
Address of the new color palette
set palette
Retain resolution
Physical base
Logical base
setscreen
170
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7 Setcolor set color
C: int Setcolor (colornum, color)
int colornum, color
Assembler:
move.w color, -(sp)
move.w colornum, - (sp)
move.w #7,-(sp)
trap #14
addq.l #6,sp
This function allows just one color to be changed. The color number (0-15)
and the color belonging to it (0-$777) must be specified. If -1 is given as the
color, the color is not set but the previous color is returned.
Example:
move.w #$777,- (sp)
move.w #1, - (sp)
move.w #7,-(sp)
trap #14
addq .1 # 6 , sp
Color white
As color number 1
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8 Floprd read diskette sector
C: int Floprd (buffer, filler, dev, sector, track, side,
count)
long buffer, filler;
int dev, sector, track, side, count;
Assembler:
move.w count, -(sp)
move.w side,-(sp)
move.w track, -(sp)
move.w sector, -(sp)
move.w dev,-(sp)
clr.l -(sp)
move.l buffer, -(sp)
move.w #8, - (sp)
trap #14
add.l #20, sp
This function reads one or more sectors in from the diskette. The parameters
have the following meaning:
count : Specifies how many sectors are to be read. Values between
one and nine (number of sectors per track) are possible.
side: Selects the diskette side, zero for single-sided drives and
zero or one for double-sided drives.
track: Determines the track number (0-79 for 80-track drives or
0-39 for 40-track drives).
sector : The sector number of the first sector to be read (0-9).
dev : Determine drive number, 0 for drive A and 1 for drive B.
filler: Unused long word.
buffer: Buffer in which the diskette data should be written. The
buffer must begin on a word boundary and be large enough
for the data to be read (512 bytes times the number of
sectors).
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The function returns an error code which has the following meaning:
0 OK, no error
-1 General error
-2 Drive not ready
-3 Unknown command
-4 CRC error
-5 Bad request, invalid command
-6 Seek error, track not found
-7 Unknown media (invalid boot sector)
-8 Sector not found
-9 (No paper)
-10 Write error
-11 Read error
-12 General error
-13 Diskette write protected
-14 Diskette was changed
-15 Unknown device
-16 Bad sector (during verify)
-17 Insert diskette (for connected drive)
Example:
move.w #1, - (sp)
move.w #0,-(sp)
move.w #0,-(sp)
move.w #1, - (sp)
move.w #l,-(sp)
clr.l -(sp)
move.l #buf fer, - (sp)
move.w #8,-(sp)
trap #14
add. 1 #20, sp
tst dO
bmi error
buffer ds.b 512
Read a sector
Page zero
Track zero
Sector one
Drive B
f loprd
Did error occur?
yes
Buffer for a sector
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9 Flopwr write diskette sector
C: int Floprd (buffer, filler, dev, sector, track, side,
count)
long buffer, filler;
int dev, sector, track, side, count;
Assembler:
move.w count, -(sp)
move . w side,-(sp)
move.w track, -(sp)
move.w sector, -(sp)
move.w dev,-(sp)
clr.l -(sp)
move . 1 buffer, -(sp)
move.w #9, - (sp)
trap #14
add. 1 #20, sp
One or more sectors can be written to disk with this XBIOS function. The
parameters have the same meaning as for the Floprd function. The function
returns an error code which has the same meaning as for reading sectors
Example:
move.w #3,- (sp)
move.w #0, - (sp)
move.w #7, - (sp)
move.w # 1 , — ( sp)
move.w #0, - (sp)
clr.l -(sp)
move . 1 #buffer,- (sp)
move.w #9, - (sp)
trap #14
add.l #20, sp
tst d0
bmi error
buffer ds.b 3*512
Write three sectors
Side zero
Track seven
Sector one
Drive A
Address of the buffer
flopwr
Did an error occur?
yes
Buffer for three sectors
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10 Flopfmt format diskette
C: int Flopfmt (buffer, filler, dev, spt, track, side,
interleave, magic, virgin)
long buffer, filler, magic;
int dev, spt, track, side, interleave, virgin;
Assembler:
move.w virgin, -(sp)
move . 1 magic, -(sp)
move.w interleave, - (sp)
move.w side,-(sp)
move.w track, -(sp)
move.w spt,-(sp)
move.w dev,-(sp)
clr.l -(sp)
move.l buffer, -(sp)
move.w #10, -(sp)
trap #14
add.l #26, sp
This routine serves to format a track on the diskette. The parameters have
the following meanings:
virgin :
The sectors are formatted with this value. The
standard value is $E5E5. The high nibble of each byte
may not contain the value $F.
magic :
The constant $87654321 must be used as magic or
formatting will be stopped.
interleave:
Determines in which order the sectors on the disk will
be written, usually one.
side :
Selects the disk side (0 or 1).
track :
The number of the track to be formatted (0-79).
spt :
Sectors per track, normally 9.
dev :
The drive, 0 for A and 1 for B.
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filler: Unused long word.
buffer : Buffer for the track data; for 9 sectors per track the
buffer mst be at least 8K large.
The function returns an error code as its result. The value -16, bad sectors,
means that data in some sectors could not be read back correctly. In this
case the buffer contains a list of bad sectors (word data, terminated by
zero). You can format these again or mark the sectors as bad.
Example:
move . w #$E5E5, - (sp)
move . 1 #$87654321,- (sp)
move . w #1 , — ( sp)
move . w #0, - (sp)
move . w #79, -(sp)
move . w #9,- (sp)
move . w #0, - (sp)
clr.l -(sp)
move.w #buf fer, - (sp)
move . w #10, -(sp)
trap #14
add. 1 #26, sp
tst dO
bmi error
buffer ds.b $2000 8K buffer
Initial data
magic
interleave
side 0
track 79
9 sector per track
drive A
f lopfmt
11 Unused
Abacus Software
Atari ST Internals
12 Midiws write string to MIDI interface
C: void Midiws (count, ptr)
int count;
long ptr;
Assembler:
move . 1 ptr, - (sp)
move.w count,- (sp)
raove.w #12, -(sp)
trap #14
addq.l #8,sp
With this function it is possible to output a string to the MIDI interface
(MIDI OUT). The parameter ptr must point to a string, count must contain
the number of characters to be sent minus 1.
Example:
move . 1 #string, - (sp) Address of the string
move.w #stringend-string-l, - (sp) Length
move.w #12,- (sp) midiws
trap #14
addq.l #8,sp
string dc.b 'MIDI data"
stringend equ *
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13 Mfpint initialize MFP format
C: void Mfpint (number, vector)
int number;
long vector;
Assembler:
move . 1 vector, -(sp)
move.w number, -(sp)
move . w #13, -(sp)
trap #14
addq.l #8,sp
This function initializes an interrupt routine in the MFP. The number of the
MFP interrupt is in number while vector contains the address of the
corresponding interrupt routine. The old interrupt vector is overwritten.
Example:
move . 1 #busy , - ( sp)
move.w #0, - (sp)
move.w #13, -(sp)
trap #14
addq.l #8,sp
busy :
Busy interrupt routine
Vector number 0
mfpint
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14 Iorec return record buffer
C: long Iorec (dev)
int dev;
Assembler:
move.w dev,-(sp)
move.w #14, -(sp)
trap #14
addq.l #4,sp
This function fetches a pointer to a buffer data record for an input device.
The following input devices can be specified:
dev Input device
0 RS-232
1 Keyboard
2 MIDI
The buffer record for an input device has the following layout:
long
ibuf
Pointer to an input buffe
int
ibuf size
Size of the input buffer
int
ibuf hd
Head index
int
ibuf tl
Tail index
int
ibuf low
Low water mark
int
ibufhi
High water mark
The input buffer is a circular buffer; the head index specifies the next write
position (the buffer is filled by an interrupt routine) and the tail index
specifies from where the buffer can be read. If the head and tail indices are
the same, the buffer is empty. The low and high marks are used in
connection with the communications status for the RS-232 (XON/XOFF or
RTS/CTS). If the input buffer is filled up to the high water mark, the
sender is informed via XON or CTS that the computer cannot receive any
more data. When data received by the computer can be processed again, so
that the buffer contents sink below the low water mark, the transfer is
resumed.
There is an identically-constructed buffer record for the RS-232 output
which is located directly behind the input record.
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The following table contains the data for all devices:
RS-
-232 input
RS-232 output
Keyboard
MIDI
Address
$9D0
($9DE)
$942
$A00
Buffer address
$6D0
$7D0
$8D0
$950
Buffer length
$100
$100
$80
$80
Head index
0
0
0
0
Tail index
0
0
0
0
Low water mark
$40
$40
$20
$20
High water mark
$C0
$C0
$20
$20
Head and tail indices are naturally dependent on the current operating mode.
High and low water marks are set at 3/4 and 1/4 of the buffer size They
have significance only for XON/XOFF or RTS/CTS in connection with
RS-232.
Example:
move.w #l,-(sp) Buffer record for keyboard
move . w #14, -(sp) iorec
trap #14
addq.l #4,sp
Result: $9F2
Abacus Software
Atari ST Internals
1
15 Rsconf set RS-232 configuration
C: void Rsconf (baud, Ctrl, ucr, rsr, tsr, scr)
int baud, Ctrl, ucr, rsr, tsr, scr;
Assembler:
move.w scr,-(sp)
move.w tsr,-(sp)
move.w rsr,-(sp)
move.w ucr,-(sp)
move.w Ctrl, - (sp)
move.w baud,-(sp)
move.w #15, -(sp)
trap #14
add.l #14, sp
This XBIOS function serves to configure the RS-232 interface. The
parameters have the following significance:
scr: Synchronous Character Register in the MFP
tsr: Transmitter Status Register in the MFP
rsr: Receiver Status Register in the MFP
ucr: USART Control Register in the MFP
Ctrl: Communications parameters
baud: Baud rate
See the section on the MFP 68901 for information on the MFP registers. If
one of the parameters is -1, the previous value is retained. The handshake
mode can be selected with the Ctrl parameter:
Ctrl Meaning
0 No handshake, default after power-up
1 XON/XOFF
2 RTS/CTS
3 XON/XOFF and RTS/CTS (not useful)
The baud parameter contains an indicator for the baud rate:
baud baud rate
0 19200
1 9600
2 4800
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baud
baud rate
3
3600
4
2400
5
2000
6
1800
7
1200
8
600
9
300
10
200
11
150
12
134
13
110
14
75
15
50
Example:
move . w #— 1 , — ( sp)
move.w #— 1 , — ( sp)
move . w #— 1 , — ( sp)
move.w #-l,-(sp)
move.w #1, - (sp)
move.w #9, - (sp)
move.w #15, -(sp)
trap #14
add.l #14, sp
Don't change MFP registers
XON/XOFF
300 baud
rsconf
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1
16 Keytbl set keyboard table
C: long Keytbl (unshift , shift, capslock)
long unshift, shift, capslock;
Assembler:
move . 1 capslock, - (sp)
move.l shift, -(sp)
move.l unshift, - (sp)
move.w #16, -(sp)
trap #14
add.l #14, sp
With this function it is possible to create a new keyboard layout. To do this
you must pass the address of the new tables which contain the key codes for
normal keys (without shift), shifted keys, and keys with caps lock. The
function returns the address of the vector table in which the three keyboard
table pointers are located. If a table should remain unchanged, -1 must be
passed as the address. A keyboard table must be 128 bytes long. It is
addressed via the key scan code and returns the ASCII code of the given
key.
Example:
move . 1 #-l, - (sp)
move.l #shift,-(sp)
move.l #unshift, - (sp)
move.w #16, -(sp)
trap #14
addq.l #14, sp
Don't change caps lock
Shift table
Table without shift
shift :
unshift :
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17 Random return random number
C: long Random ()
Assembler:
move . w #17, -(sp)
trap #14
addq.l #2,sp
This function returns a 24-bit random number. Bits 24-31 are zero. With
each call you receive a different result. After turning on the computer a
different seed is created.
Example:
move.w #17, -(sp) random
trap #14
addq.l #2,sp
18 Protobt produce boot sector
C: void Protobt (buffer, serialno, disktype, execflag)
long buffer, serialno;
int disktype, execflag;
Assembler:
move.w execflag, - (sp)
move.w disktype, - (sp)
move.l serialno, - (sp)
move . 1 buffer, -(sp)
move.w #18, -(sp)
trap #14
add. 1 #14, sp
This function serves to create a boot sector. A boot sector is located on track
0, sector 1 on side 0 of a diskette and gives the DOS information about the
disk type. If the boot sector is executable, it can be used to load the
operating system. With this function you can create a new boot sector, for a
different disk format or to change an existing boot sector.
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The parameters:
execf lag: determines if the boot sector is executable.
0 not executable
1 executable
-1 boot sector remains as it was
The disk type can assume the following values:
0 40 track, single sided (180 K)
1 40 track, double sided (360 K)
2 80 track, single sided (360 K)
3 80 track, double sided (720 K)
-1 Disk type remains unchanged
The parameter seriaino is a 24-bit serial number which is written in the
boot sector. If the serial number is greater than 24 bits ($01000000), a
random serial number is created (with the above function). A value of -1
means that the serial number will not be changed.
The parameter buffer is the address of a 512-byte buffer which contains
the boot sector or in which the boot sector will be created.
A boot sector has the following construction:
Address 40 track SS 40 track DS 80 track SS 80 track DS
0- 1
Branch
instruction to
boot program
if executable
2- 7
' Loader ’
8-10
24-bit
serial
number
11-12
BPS
512
512
512
512
13
SPC
1
2
2
2
14-15
RES
1
1
1
1
16
FAT
2
2
2
2
17-18
DIR
64
112
112
112
19-20
SEC
360
720
720
1440
21
MEDIA
252
253
248
249
22-23
SPF
2
2
5
5
24-25
SPT
9
9
9
9
26-27
SIDE
1
2
1
2
28-29
HID
0
0
0
0
510-511
CHECKSUM
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bps: Bytes per sector. The sector size is 5 1 2 bytes for all formats
spc : Sectors per cluster. The number of sectors which are combined
into one block by the DOS, 2 sectors equals IK
res : Number of reserved disk sectors including the boot sector.
FAT : The number of file allocation tables on the disk.
dir : The maximum number of directory entries.
sec : The total number of sectors on the disk.
MEDIA: Media descriptor byte, not used by the ST-BIOS.
spf : Number of sectors in each FAT.
spt : Number of sectors per track.
s IDE : Number of sides of the diskette.
hid : Number of hidden sectors on the disk.
The boot sector is compatible with MS-DOS 2.x. This is why all 16-bit
words are stored in 8086 format (first low byte, then high byte). If the
checksum of the whole boot sector is $1234, the sector is executable. In this
case the boot program is located at address 30.
This program adapts an existing boot sector for 80 tracks, double sided.
Example:
move . w
#-l, - (sp)
move . w
#3, - (sp)
move . 1
#-l, - (sp)
move . 1
#buf fer, - (sp)
move . w
#18, - (sp)
trap
#14
add. 1
#14, sp
Don't change executability
80 tracks DS
Don't change serial number
protobt
buffer ds.b 512
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19 Flopver verify diskette sector
C: int Flopver (buffer, filler, dev, sector, track, side, count)
long buffer, filler;
int dev, sector, track, side, count;
Assembler:
move.w count, -(sp)
move.w side,-(sp)
move.w track,- (sp)
move.w sector, -(sp)
move.w dev,-(sp)
clr.l -(sp)
move . 1 buffer, -(sp)
move.w #19, -(sp)
trap #14
add.l #16, sp
This function verifies one or more sectors on the disk. The sectors are read
from the disk and compared with the buffer contents in memory. The
parameters are the same as for reading and writing sectors. If the sector and
buffer contents agree, the result will be zero. If an error occurs, an error
number will be returned in DO (see Read sector for error codes). On an
error, the buffer will contain a list of bad sectors (16-bit values) terminated
by a zero word. If Rwabs was used to write the sectors and if fverify
($444) is set, the sectors will automatically be verified after they are written.
Example:
move . w
#1, - (sp)
A sector
move . w
#0, - (sp)
Side zero
move . w
#39, -(sp)
Track 39
move . w
# 1 , — ( sp)
Sector 1
move . w
#0,- (sp)
Drive A
clr.l
- (sp)
move . 1
#buf fer, - (sp)
Buffer address
move . w
#19, - (sp)
flopver
trap
#14
add. 1
#16, sp
tst
dO
Error?
bmi
error
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20 Scrdmp output screen dump
C: void Scrdmp ()
Assembler:
move.w #20, -(sp)
trap #14
addq.l #2,sp
This function sends a hardcopy of the screen to a connected printer. The
previously-set printer parameters ("desktop Printer setup") are used. You
can also perform this function by simultaneously pressing the ALT and
HELP keys or from the desktop through "Print Screen" from the "Options"
menu.
Example:
move.w #20, -(sp) Hardcopy
trap #14 Call XBIOS
addq.l #2,sp
21 Cursconf set cursor configuration
C: int Cursconf (function, rate)
int function, rate;
Assembler:
move.w rate,-(sp)
move.w function, - (sp)
move.w #21, -(sp)
trap #14
addq.l #6,sp
This XBIOS function serves to set the cursor function. The parameter
function can have a value from 0-5, which have the following meanings:
function meaning
0 Disable cursor
1 Enable cursor
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function
2
3
4
5
meaning
Flashing cursor
Steady cursor
Set cursor flash rate
Get cursor flash rate
You can use this function to set whether the cursor is visible, and whether it
is flashing or steady. The XBIOS function returns a result only if you fetch
the old baud rate. The unit of the flash frequency is dependent on the screen
frequency: It is 70 Hz for a monochrome monitor or 50 Hz for a color
monitor. You can set a new flash rate with function number 5. You need
only use the parameter rate if you want to pass a new flash rate.
Example:
move.w #20, -(sp)
move.w #4,-(sp)
move.w #21, -(sp)
trap #14
addq.l #6,sp
20/70 seconds
Set flash rate
cursconf
22 Settime set clock time and date
C: void Settime (time)
long time;
Assembler:
move . 1 time,-(sp)
move.w #22,- (sp)
trap #14
add.l #6,sp
This function is used to set the clock time and date. The time is passed in the
lower word of time and the date in the upper word. The time and date are
coded as follows:
bits 0- 4
bits 5-10
bits 11-15
bits 16-20
Seconds in two-second increments
Minutes
Hours
Day 1-31
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bits 21-24 Month 1-12
bits 25-31 Year 0-119 (minus offset 1980)
Example:
move . 1 #%1011001100000100000000000000,-(sp)
move.w #22, -(sp) settime
trap #14
addq .1 # 6 , sp
This call sets the date to the 16th of September, 1985, and the clock time to
8 o'clock.
23 Gettime return clock time and date
C: long Gettime ()
Assembler:
move.w #23, -(sp)
trap #14
addq.l #2,sp
This function returns the current date and clock time in the following format:
bits 0- 4 Seconds in two-second increments
bits 5-10 Minutes
bits 11-15 Hours
bits 16-20 Day 1-31
bits 21-24 Month 1-12
bits 25-31 Year (minus offset 1980)
Example:
move.w #23, -(sp) gettime
trap #14
addq.l #2,sp
move . 1 d0,time Save time and date
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Abacus Software
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24 Bioskeys restore keyboard table
C: void Bioskeys ()
Assembler:
move.w #24, -(sp)
trap #14
addq.l #2,sp
If you have selected a new keyboard layout with the XBIOS function 16,
keytbl, this function will restore the standard BIOS keyboard layout. You
can call this function, for example, before exiting a program of your own
which changed the keyboard layout.
Example:
move.w #24, -(sp) bioskeys
trap #14
addq.l #2,sp
25 Ikbdws intelligent keyboard send
C: void Ikbdws (number, pointer)
int number;
long pointer;
Assembler:
move.l pointer, - (sp)
move.w number, -(sp)
move.w #25, -(sp)
trap #14
addq.l #8,sp
This XBIOS function serves to transmit commands to the keyboard
processor (intelligent keyboard). The parameter pointer is the address of a
string to be sent, number is the length of a string minus 1.
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Example:
move . 1 tstring, - (sp) Address of the string
move.w #strend-st ring-1, - (sp) Length minus 1
move.w #25, -(sp) ikbdws
trap #14
addq.l #8,sp
string dc.b $80,1
st rend equ *
26 Jdisint disable interrupts on MFP
C: void Jdisint (number)
int number;
Assembler:
move.w number, -(sp)
move.w #26, -(sp)
trap #14
addq.l #4,sp
This function makes it possible to selectively disable interrupts on the MFP
68901. The parameter is the MFP interrupt number (0-15). The significance
of the individual interrupts is described in the section on interrupts.
Example:
move.w #10,- (sp) Disable RS-232 transmitter interrupt
move.w #26,- (sp) Disable interrupt
trap #14
addq.l #4,sp
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1
27 Jenabint enable interrupts on MFP
C: void Jenabint (number)
int numbe r ;
Assembler:
raove.w number, -(sp)
move.w #27, -(sp)
trap #14
addq.l #4,sp
This function can be used to re-enable an interrupt on the MFP. The
parameter is again the number of the interrupt, 0-15.
Example:
move.w #12, -(sp) Enable RS-232 receiver interrupt
move.w #27,- (sp) Enable interrupt
trap #14
addq.l #4,sp
28 GiaCCeSS access GI sound, chip
C: char Giaccess (data, register)
char data;
int register;
Assembler:
move.w #register, - (sp)
move.w #data,-(sp)
move.w #28, -(sp)
trap #14
addq.l #6,sp
This function allows access to the GI sound chip registers, register must
contain the register number of the sound chip (0-15). The meaning of the
individual registers is given in the hardware description of the sound chip.
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Bit 7 of the register number determines whether the specified register will be
written or read:
Bit 7 0 : Read
1 : Write
When writing, an 8-bit value is passed in data; when reading, the function
returns the contents of the corresponding register.
Example:
move.w #$80+3, -(sp) Write register 3
move.w #$50,- (sp) Value to write
move.w #28, -(sp)
trap #14
addq.l #6,sp
29 Offgibit reset Port A GI sound chip
C: void Of fgibit (bitnumber)
int bitnumber;
Assembler:
move.w #bitnumber, - ( sp)
move.w #29, -(sp)
trap #14
addq.l #4,sp
A bit of port A of the sound chip can be selectively set with this function
call. Port A is an 8 -bit output port in which the individual bits have the
following function:
Bit 0: Select disk side 0/side 1
Bit 1 : Select drive A
Bit 2 : Select drive B
Bit 3: RS-232 RTS (Request To Send)
Bit 4: RS-232 DTR (Data Terminal Ready)
Bit 5: Centronics strobe
Bit 6: General Purpose Output
Bit 7 : unused
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Example:
move.w #4,-(sp) DTR bit
move.w #29,- (sp) offgibit
trap #14
addq.l #4,sp
30 Ongibit clear Port A of GI sound chip
C: void ongibit (bitnumber)
int bitnumber;
Assembler:
move.w #bitnumber, - (sp)
move.w #30,- (sp)
trap #14
addq.l #4,sp
This function is the counterpart of the previous function. With this it is
possible to clear a bit of port A in the sound chip.
Example:
move.w #4,-(sp) DTR bit
move.w #30,- (sp) ongibit
trap #14
addq .1 # 4 , sp
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31 Xbtimer start MFP timer
C: void Xbtimer (timer, control, data, vector)
int timer, control, data;
long vector;
Assembler:
move . 1 vector, -(sp)
move.w data,-(sp)
move.w control, - (sp)
move.w timer, -(sp)
move.w #31, -(sp)
trap #14
add.l #12, sp
This function allows you to start a timer in the MFP 68901 and assign an
interrupt routine to it. timer is the number of the timer in the MFP:
Timer A : 0 / Timer B : 1 / Timer C : 2 / Timer D : 3
The parameters data and control are the values placed in the control and
data registers of the timer (see the hardware description of the MFP 68901).
The parameter vector is the address of the interrupt routine which will be
executed when the timer runs out. The four timers in the MFP are already
partly used by the operating system:
Timer A:
Timer B:
Timer C:
Timer D:
Reserved for the end user
Horizontal blank counter
200 Hz system timer
RS-232 baud rate generator (interrupt vector free)
Example:
move.l #vector, - (sp)
move.w data,-(sp)
move.w control, - (sp)
move.w #0,-(sp)
move.w #31, -(sp)
trap #14
add.l #12, sp
Interrupt routine
Data and
Control registers
Timer A
xbtimer
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32 DoSOlind set sound parameters
C: void Dosound (pointer)
long pointer;
Assembler:
move.l pointer, - (sp)
move.w #32, -(sp)
trap #14
addq.l #6,sp
This function allows for easy sound processing. The parameter pointer
must point to a string of sound commands. The following commands can be
used:
Commands $00-$0F
These commands are interpreted as register numbers ol the sound
chip. A byte following this is loaded into the corresponding register.
Command $80 , , . .
An argument follows this command which will be loaded into a
temporary register.
Command $81 .
Three arguments must follow this command. The first argument is the
number of the sound chip register in which the contents of the
temporary register will be loaded. The second argument is a two s-
complement value which will be added to the temporary register. The
third argument contains an end criterion. The end is reached when the
content of the temporary register is equal to the end criterion.
Commands $82-$FF
One argument follows each of these commands. If this argument is
zero, the sound processing is halted. Otherwise this argument
specifies the number of timer ticks (20ms, 50Hz) until the next sound
processing.
Example:
move.l #pointer, - (sp) Pointer to sound command
move.w #32, -(sp) dosound
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trap #14
addq.l #6,sp
pointer dc.b 0,10,1,50,...
33 Setprt set printer configuration
C: void Setprt (config)
int config;
Assembler:
move.w config, -(sp)
move.w #33, -(sp)
trap #14
addq.l #4,sp
This function allows the printer configuration to be read or changed. If
config contains the value -1, the current value is returned, otherwise the
value is accepted as the new printer configuration. The printer configuration
is a bit vector with the following meaning:
Bit number 0
1
0
1
2
3
4
5
6-14
15
matrix printer
monochrome printer
Atari printer
Test mode
Centronics port
Continuous paper
reserved
always 0
daisy-wheel
color printer
Epson printer
Quality mode
RS-232 port
Single-sheet
Example:
move.w #%000100, - (sp) Epson printer
move.w #33, -(sp) setprt
trap #14
addq.l #4,sp
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1
34 Kbdvbase return keyboard, vector table
C: long Kbdvbase ()
Assembler:
move.w #34, -(sp)
trap #14
addq.l #2,sp
This XBIOS function returns a pointer to a vector table which contains the
address of routines which process the data from the keyboard processor.
The table
is constructed as follows:
long
midivec
MIDI input
long
vkbderr
Keyboard error
long
vmiderr
MIDI error
long
statvec
IKBD status
long
mousevec
Mouse routines
long
ciockvec
Clock time routine
long
joyvec
Joystick routines
long
midisys
MIDI system vector
long
ikbdsys
IKBD system vector
The parameter midivec points to a routine which writes data received from
the MIDI input (byte in DO) to the MIDI buffer.
The parameters vkbderr and vmiderr are called when an overflow is
signaled by the keyboard or MIDI ACIA.
The routines statvec, mousevec, ciockvec, and joyvec process the data
packages which come from the keyboard ACIA. A pointer to the packages
received is passed to these routines in DO. The mouse vector is used by
GEM. If you want to use your own routine, you must terminate it with RTS
and processing time may take no longer than one millisecond.
The remaining routines midisys and ikbdsys are called when there is a
character in the present ACIA. midisys holds the character and jumps to
midivec; ikbdsys gets the data package from the ACIA, and branches to
the abovementioned routines.
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Example:
move.w #34,- (sp) kbdvbase
trap #14
addq.l #2,sp
We get $DCC as the result. The vector field contains the following values:
midivec
$FC2CE2/$8B70
vkbderr
$FC288E/$871C
(RTS)
vmiderr
$FC288E/$871C
(RTS)
statvec
$FC230A/$8198
(RTS)
mousevec
$FD02C2/ $16150
clockvec
$FC1D12/$7BA0
joyvec
$FC230A/ $8198
(RTS)
midisys
$FC284A/$86D8
ikbdsys
$FC285A/$86E8
35 Kbrate set keyboard repeat rate
C: int Kbrate (delay, repeat)
int delay, repeat;
Assembler:
move.w repeat, -(sp)
move.w delay, -(sp)
move.w #35, -(sp)
trap #14
addq.l #6,sp
The keyboard repeat can be controlled with this function. The parameter
delay specifies the delay time after a key is pressed before the key will
automatically be repeated. The parameter repeat determines the time span
after which the key will be repeated again. These values can be changed
from the desktop by means of the two slide controllers on the control panel.
The times are based on the 50 Hz system clock. If -1 is specified for one of
the parameters, the corresponding value is not set. The function returns the
previous values as the result; bits 0-7 contain the repeat value and bits
8-15 the value of delay.
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Example:
move . w #-1/ - (sp) Read old values
move.w #-l,-(sp)
move.w #35, -(sp) kbrate
trap #14
addq.l #6,sp
Result: DO = $0B03
36 Prtblk output block to printer
C: void Prtblk (parameter)
long parameter;
Assembler:
move.l parameter, - (sp)
move.w #36, -(sp)
trap #14
addq .1 # 6 , sp
This function resembles and is used by the function Scrdmp (20). The
function expects a parameter list, however, whose address is passed to it.
This list is constructed as follows:
long
blkprt
Address of the screen RAM
int
offset
int
width
Screen width
int
height
Screen height
int
left
int
right
int
scrres
Screen resolution (0, 1, or :
int
dstres
Printer resolution (0 or 1)
long
colpal
Address of the color palette
int
type
Printer type (0-3)
int
port
Printer port (0=Centronics,
long
masks
Pointer to half-tone mask
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Example:
move . 1 tparameter,
move . w #3 6, - (sp)
trap #14
addq.l #6,sp
-(sp) Address of the parameter block
prtblk
parameter dc . 1 ...
37 Vsync
wait for video
C : void Vsync ( )
Assembler:
move . w #37, -(sp)
trap #14
addq.l #2,sp
This function waits for the next picture return. It can be used to synchronize
graphic outputs with the beam return, for example.
Example:
move.w #37,- (sp)
trap #14
addq.l #2,sp
wait for vsync
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38 Supexec
set supervisor execution
C: void Supexec (address)
long address;
Assembler:
move . 1 address, - (sp)
move.w #38, -(sp)
trap #14
addq.l #6,sp
A routine can be executed in supervisor mode with Supexec.
Example:
move . 1 #address , (sp)
move.w #38, -(sp)
trap #14
addq.l #6,sp
address move . 1 $400,00
39 Puntaes disable AES
C: void Puntaes ()
Assembler:
move.w #39, -(sp)
trap #14
addq.l #2,sp
The AES can be disabled with this function, provided it is not in ROM
Example:
move.w #39, -(sp)
trap #14
Abacus Software
Atari ST Internals
64 Blitmode read. and. alter blitter
C: int Blitmode (flag)
int flag;
Assembler:
move . w flag, - (sp)
move . w #64, -(sp)
trap #14
addq.l #4,sp
This function lets you read and change an available blitter's configuration.
Blitmode also lets you determine whether a blitter exists in the system (bit
1 ) and whether it is usable (bit 0). The ST reads the current configuration
when flag has a value of -1 (Oxffff). The result is a bitmask. Each bit
represents the following:
Bit number 0 1
0 Blit-operation Blit_operation
through software through hardware
1 No blitter available Blitter available
2-14 Undefined, reserved
15 Always 0
When a blitter is available, you can determine whether blit operations can be
performed by software or by the blitter. This is established by clearing or
setting bit 0. b
Bit number 0
0 Blit-operation
through software
1-14 Undefined, reserved
15 Always 0
Example:
move
#-l, (sp)
set configuration
move
#64, -(sp)
blitmode
trap
#14
addq .
1 #4, sp
btst
#1, dO
is blitter on hand?
beq
no_blit
no
l
Blit_operation
through hardware
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bset #0,d0
move dO,-(sp) blit operation through hardware
move #64, -(sp) blit-mode
trap #14
addq. 1 #4, sp
no_blit :
rts
The above sample program tests for an onboard Witter. V this is the case,
the system bit 0 displays blit operations through hardware (the blitter). The
test, once set to hardware, won’t ignore onboard blitters m the system.
Bv setting the blit mode, this should call the configuration, and the bits 1-14
fhoSSbl Sen over. They are reserved for further graphic functions or
graphic chips.
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3.4 The Graphics
Next to the high processing speed and the large memory available, the
graphics capability is certainly the most fascinating aspect of the ST. With
the standard monochrome monitor and the resolution of 640x400 points, it
creates a whole new price/performance class for itself. But also in the color
resolution the ST can display 16 colors with 320x200 screen points.
In this chapter we want to explain how the graphics are organized and how
you can create fast and effective graphics without using the GEM graphics
package, which is rather complicated for beginners. The ST offers the
assembler and C programmer very useful routines which don't exactly make
graphics programming child's play, but which can take away a good deal of
the programming work. Unfortunately, some of these functions are so
comprehensive that a detailed description would exceed the scope of this
book. We have therefore had to limit ourselves to the simpler, but no less
interesting functions.
These graphics routines are called in a very elegant manner. The software
developers have made use of the fact that there are two groups of opcodes in
the 68000 which the 68000 does not "understand" and which generate a
trap, or software interrupt, when they are encountered in a program. These
are the two groups of opcodes which begin with $Axxx and $Fxxx. In the
ST, the $Axxx opcode trap is used in order to access the graphics routines.
The trap handler, the program called by the trap, checks the lowest byte of
the "command" to see what value it has. Values between zero and $F are
permissible here. This gives a total of 16 graphics routines, which should
first be presented in an overview. Later we will talk about the actual
commands in detail.
$A000 Determine address of required variable range
$A001 Set point on the screen
$A002 Determine color of a screen point
$A003 Draw a line on the screen
$A004 Draw a horizontal line (very fast!)
$A005 Fill rectangle with color
$A006 Fill polygon line by line
$A007 Bit block transfer
$A008 Text block transfer
$A009 Enable mouse cursor
$A00A Disable mouse cursor
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$A00B Change mouse cursor form
$A00C Clear sprite
$A00D Enable sprite
$A00E Copy raster form
$A00F Contour fill (Flood fill)
These routines are the ground work for the hardware-dependent part of
GEM All GEM graphic and text output is performed by the routines ot the
$Axxx opcodes. The set of A-opcodes are very useful in games. In games
windows are needed only in the rarest cases. Another important point is the
speed of the line A-instructions. Using the graphic routines directly is
clearly faster than if the output is handled by GEM. Before we describe the
individual commands in detail, we will take a brief look at the construction
of graphics in the various graphic modes of the ST.
Immediately after turning the ST on, an area of 32K bytes is initialized at the
upper memory border as the video RAM. In normal operation this results m
addresses $78000 to $7FFFF or $F8000 to $FFFFF acting as the screen
RAM. This video RAM can be viewed as a window in j the ST lhe
following description is a simplification of the features of the 260ST with
"only" 512K.
We will start with the simplest mode, the 640x400 mode. In this case each
set of 80 bytes, or better, each set of 40 words forms one screen line. The
word with the lowest address is displayed on the left edge of the screen, t e
additional words are displayed in order from left to right. Within a wor ,
the highest-order bit lies at the left and the lowest-order bit at the right.
With this data, any point on the screen can be easily controlled or read. For
example, to set the first screen point, the value $8000 must be written mo
memory location $78000. There is one small limitation to this area, l he
position of ST screen RAM can be easily moved. For this reason it is
usually more advantageous to set the point with the A function $A001.
Function $A001 assumes an X-Y coordinate system with origin in the upper
left-hand comer, and determines the position of the video RAM itsell in
order to set the point at the proper screen location.
In this resolution mode, each screen point is represented by a bit. If the bit
is set, the point appears dark, or bright if the inverse display mode is
selected in color palette register 0. The screen consists of only one bit plane.
Different colors cannot be represented with just one plane, however. I his is
why when the resolution increases in the color modes, the number ot
displayable colors decreases.
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Figure 3.4-1 LO-RES-MODE (0)
Four colors are possible in the 640x200 resolution mode. In this mode, two
contiguous memory words form a single logical entity. The color of a point
is determined by the value of the two corresponding bits in the two words.
If both bits are zero, the background color results. Therefore two sequential
words are used together for pixel representation. For the colors, however,
all odd words belong to a plane. The second plane is made up of the even
words. In this mode, there are two planes available.
Things become quite colorful in the mode with "only" 320x200 points. In
this operating mode, 4 contiguous memory words form one entity which
determines the color of the 16 pixels. To stick to the example we used
before: in order to set the point in the upper left-hand comer, the topmost
bits of words $78000, $78002, $78004, and $78006 must be manipulated.
The desired color results from the bit pattern in the words.
It naturally requires some computer time to set a point in the desired color,
independent of the mode. All of this work is handled by the $A001 routine,
however. This routine sets all of the pertaining bits for the desired color in
the current resolution. Naturally, all four planes are present in this mode.
The first plane, keeping to our example, made up of the words at address
$7F000, $7F008, $7F010, ..., and the other planes are composed of the
other addresses correspondingly.
Another point to be clarified concerns the fonts or character sets. Since the
ST does not have a text mode, only a graphics mode, the text output is
created in high-resolution graphics. There are three different fonts built into
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the ST. You can load additional fonts from disk. Each font has a header
which contains important information about the displayable characters.
Since the important data are contained in the font header, there are unusually
few limits for display. The characters can be arbitrarily high or wide. The
age of the 8x8 matrix for character output is over. It is even possible to get
cursive, bold, true proportional or other type on the screen.
The three built-in fonts are monospaced fonts, meaning they have a fixed
defined size in pixels and a defined pitch. The smallest font has a matrix or
6x6. With a resolution of 640x400 points, 66 lines of 106 characters each
can be displayed. This font is only accessible for output under GEM, not
for output under TOS, and is used in the output of the drrectory m the icon
form for example. The next-largest type is composed of 8x8 points. 1 ms
type is used when a color monitor is connected to the ST, wh>le thethird
and largest font is used for the normal black-and-white mode. This font
uses a matrix of 8x16 points.
Figure 3.4-2 MEDIUM-RES-MODE (1)
The exact layout of the font header is found under command $A008, which
represents a very versatile text output whichg«s far beyond what ts
possible with the routine of the BIOS and GEMDOS.
Finally, we must clarify some of the terms which will come up often in the
following descriptions, whose meanings may not be so clear. These are foe
terms Contrl array. Intin array, Intout array, Ptsin array and Ptsout array.
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These arrays are mainly used by GEM to pass parameters to individual
GEM functions or to store results from these functions. But line-A
functions use parts of these arrays to pass parameters also. The arrays are
defined in memory as data areas, whereby each element in the array consists
of 2 bytes.
For GEM functions, the Contrl array always contains the number desired in
the first element (Contrl(O)). This parameter is not used by the line-A
commands, however. Contrl(l) contains the number of XY coordinates
required for the function. These coordinates must be placed in the Ptsin
array before the call. The element Contrl(2) is not supplied before the call.
After the call it contains the number of XY coordinates in the Ptsout array.
Contrl(3) specifies how many parameters will be passed to the function in
the Intin array, while Contrl(4) contains the number of parameters in the
Intout array after the call. The additional parameters of the Contrl array are
not relevant for users of the line A.
Unfortunately, not all of the A opcode parameters can be in these arrays.
For this reason there is another memory area which used as a variable area
for (almost) all graphic outputs. The functions and uses of these over 50
variables are in a table at the end of this chapter. Important variables are also
explained in conjunction with the functions requiring them.
By the way, you should be aware that registers DO to D2 and AO to A2 are
changed by calling the functions. Important values contained in these
registers should be saved before a call.
Figure 3.4-3 HI-RES-MODE (2)
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$A000 Initialize
Initialize is really the wrong expression for this function. After the call, the
addresses of the more important data areas are returned in registers DO and
AO to A2. This function does not require input parameters.
The program is informed of the starting address of the line-A variables in
DO and AO. After the call, A1 points to a table with three addresses. These
three addresses are the starting address of the three system font headers.
Register A2 points to a table with the starting addresses of the 16 line-A
routines.
This opcode destroys (at least) the contents of registers DO to D2 and AO to
A2. Important values should be saved before the call.
$A001 PUT PIXEL
This opcode sets a point at the coordinates specified by the coordinates in
pt s in ( o ) and pt sin ( l ) . The color is passed in intin (0) , ptsin (0)
contains X-coordinate, Ptsin (l) the Y-coordinate.
The coordinate system used has its origin in the upper left comer. The
possible range of the X and Y coordinates is naturally set according to the
graphic mode enabled. Overflows in the X range are not handled as errors.
Instead, the Y coordinate is simply incremented by the appropriate amount.
No output is made if the Y range is exceeded.
The color in intin (0) is dependent on the mode used. When driving the
monochrome monitor, only bit zero of the value of intin (0) is evaluated.
$A002 GET PIXEL
The color of a pixel can be determined with this opcode. As with $A001,
the XY coordinates are passed in Ptsin (0) and ptsin (l) ; the color value
is returned in the DO register.
Abacus Software
Atari ST Internals
$A003 LINE
With the LINE opcode a line can be drawn between the points with
coordinates xl,yl and x2,y2. The parameters for this function are not
passed via the parameter arrays, but must be transferred to the line-A
variables before the call. The variables used are:
_X1
= xl
coordinate
_Y1
= yi
coordinate
_X2
= x2
coordinate
_Y2
= yi
coordinate
_FG_BP_1 = Plane 1 (all three modes)
_FG_BP_2 = Plane 2 (640x200, 320x200)
_FG_BP_3 = Plane 3 (only 320x200)
_FG_BP_4 = Plane 4 (only 320x200)
_LN_MASK = Bit pattern of the line
For example: $FFFF = filled
$CCCC = broken
_WRT_MOD = Determines the write mode
_LSTLIN = This variable should be set to -1 ( $FFFF)
One point to be noted for some applications is the fact that when drawing a
line, the highest bit of the line bit pattern is always set on the left screen
edge. The line is always drawn from left to right and from top to bottom,
not from xl,yl to x2,y2.
Range overflows are handled as for PUT PIXEL. If an attempt is made to
draw a line from 0,0 to 650,50, a line is actually drawn from, 0,0 to
639,48. The "remainder" results in an additional line from 0,49 to 10,50.
A total of four different write modes, with values 0 to 3, are available for
drawing lines. With write mode zero, the original bit pattern "under" the line
is erased and the bit pattern determined by _ln_mask is put in its place
(replace mode). In the transparent mode (_wrt_mod=i), the background, the
old bit pattern, is ORed with the new line pattern so only additional points
are set. In the XOR mode (_wrt_mod=2), the background and the line
pattern are exclusive-ored. The last mode (_wrt_mod=3) is the so-called
"inverse transparent mode." As in the transparent mode, it involves an OR
combination of the foreground and background data, in which the
foreground data, the bit pattern determined by _ln_mask, are inverted
before the OR operation.
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$A004 HORIZONTAL LINE
This function draws a line from xl,yl to x2,yl. Drawing a horizontal line is
significantly faster than when a line must be drawn diagonally. Diagonal
lines are also created with this function, in which the line is divided into
multiple horizontal lines segments. The parameters are entered directly into
the required variables.
XI
= xl
coordinate
_yi
= yi
coordinate
X2
= x2
coordinate
_FG_BP_1 = Plane 1 (all three modes)
_FG_BP_2 = Plane 2 (640x200, 320x200)
_FG_BP_3 = Plane 3 (only 320x200)
FG BP_4 = Plane 4 (only 320x200)
WRT MOD = Determines the write mode
3>atptr = Pointer to the line pattern to use
_patmsk = "Mask” for the line pattern
The valid values in wrt mod also lie between 0 and 3 for this call. The
contents of the variable _patptr is the address at which the desired line
pattern or fill pattern is located. The H-line function is very well-suited to
creating filled surfaces. The variable jpatmsk plays an important role in
this. The number of 16-bit values at the address in _jp atptr is dependent
on the its value. If, for example, _patmsk contains the value 5, six 16-bit
values should be located at the address in _patptr as the line pattern. If a
horizontal line with the Y-coordinate value zero is to be drawn, the first bit
pattern is taken as the line pattern. The second word is taken as the pattern
for a line drawn at Y -coordinate 1 , and so on. The pattern for a line with
Y-coordinate 6 is again determined by the first value in the bit table. In this
manner, very complex fill patterns can be created with relatively little effort.
$A005 FILLED RECTANGLE
The opcode $A005 represents an extension, or more exactly a special use,
of opcode $A004. It is used to created filled rectangles. The essential
parameters are the coordinates of the upper left and lower right comers of
the of the rectangle.
XI
= xl
coordinate.
left upper
_Yi
= yi
coordinate
X2
= x2
coordinate.
right lower
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_Y2
_FG_BP_1
_FG_BP_2
_FG_BP_3
_FG_BP_3
_WRT_MOD
_jpatptr
_patmsk
_CLIP
_XMN__CLIP
_XMX_CLIP
_YMN_CLIP
YMX CLIP
y2 coordinate
Plane 1 (all three modes)
Plane 2 (640x200, 320x200)
Plane 3 (only 320x200)
Plane 4 (only 320x200)
Determines the write mode
Pointer to the fill pattern used
"Mask" for the fill pattern
Clipping flag
X minimum for clipping
X maximum for clipping
Y minimum for clipping
Y maximum for clipping
We have already explained all of the variables except the "clipping"
variables. What is clipping? Clipping creates extracts or clippings of the
total picture. If the clipping flag is set to one (or any value not equal to
zero), the rectangle, drawn by $A005, is displayed only in the area defined
by the clipping-area variables. An example may explain this behavior better:
The values 100,100 and 200,200 are specified as the coordinates. The clip
flag is 1 and the clip variables contain the values 150,150 for xmn clip and
ymn clip as well as 300,300 for xmx_clip and ymx clip. The value
$FFFF will be chosen as the fill value for all of the lines. With these values,
the rectangle will have the coordinate 150,150 as the upper left comer and
200,200 as the lower right. The "missing" area is not drawn because of the
clip specifications. Clearing the clip flag draws the rectangle in the originally
desired size.
$A006 FILLED POLYGON
$ A006 is also an extension of $ A004. Areas can be filled with a pattern with
this function. The entire surface is not filled with the call: just one raster line
is filled, a horizontal line with a width of one point. The result is that there
are significantly more options for influencing the fill pattern.
The necessary variables are:
Ptsin
Contrl (1)
_Y1
_FG_BP_1
FG BP 2
= Array with the XY coordinates
= Number of coordinate pairs
= yl coordinate
= Plane 1 (all three modes)
= Plane 2 (640x200, 320x200)
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FG_BP_3 = Plane 3 (only 320x200)
FG BP 3 = Plane 4 (only 320x200)
WRT MOD = Determines the write mode
_patptr = Pointer to the fill pattern used
_patmsk = "Mask” for the fill pattern
_CLIP = Clipping flag
XMN CLIP = X minimum for clipping
XMX_CLIP = X maximum for clipping
YMN CLIP = Y minimum for clipping
YMX CLIP = Y maximum for clipping
Basically, all of the parameters here are to be set exactly as they might be for
a call to $A005. Only the first three coordinates are different. The XY
coordinates are stored in the Ptsin array. It is important you specify the
start coordinate again as the last coordinate as well. In ^ a tomge,
you must, for example, enter the coordinates (320,100), (1ZU,3UU),
(520 300), and (320,100). The number of effective coordinate pairs, three
in our example, must be placed in contri (l) , the second element of the
array. With a call to the $A006 function you must also specify the
Y-coordinate of the line to be drawn. Naturally you can fill all Y-coordinates
from 0 to 399 (0 to 199 in the color modes) in order. But it is faster to find
the largest and smallest of the XY values and call the function with only
these as the range.
$A007 BITBLT
The BITBLock Transfer function copies a square source range into a target
area. The source range can combine with a raster. Source and target range
can be combined with 16 different logical operations. You can have these at
any address. Normally it is at least the target area of video RAM; but it can
also be copied within the screen or from an unused part of memory to
another. If a blitter is onboard the ST, BITBLT uses hardware.
BITBLT is used by the line-A functions TEXTBLT and COPY RASTER
FORM as well as the VDI functions Copy Raster Opaque (vro^cpyfm) and
Copy Raster Transparent (vrt_cpyfm). BITBLT's versatility involves the
parameters used with the function call. These parameters are source,
destination and pattern; information about the number of bitplanes (color or
b/w) used; and logical operations combining source and destination. I he
data stands in a 76-byte parameter block, whose function address must be
given through register A6. The parameter block looks like this.
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Offset Length Name
0
W
s_width
Pixel width of range being edited
2
W
2_height Pixel height of range being edited
4
w
planes
Number of bit planes
6
w
fg-col
Foreground color
8
w
bg_col
Background color
10
L
op_tab
Logical operation
14
w
s_xmin
Source upper left X-coordinate
16
w
s_ymin
Source upper left Y-coordinate
18
L
s_f orm
Source starting address
22
W
s_nxwd
Byte offset of next source line
24
W
s_nxln
Byte offset of next source line
26
W
s_nxpl
Byte offset of next source color plane
28
W
d_xmin
Destination upper left X-coordinate
30
W
d_ymin
Destination upper left Y-coordinate
32
L
d_f orm
Start address through destination
36
W
d_nxwd
Byte offset of next destination word
38
W
d nxln
Byte offset of next destination line
40
W
d_nxpl
Next destination color plane
42
L
p_addr
Start address of pattern
46
W
p_nxln
Byte offset of next raster line
48
W
p__nxpl
Byte offset of next color plane
50
W
p mask
Raster height (raster index mask)
52
12W
filler
Used internally by BITBLT
When destination and/or source ranges appear on the screen, the following
values are used:
Resolution
Bitplanes
d_f orm/ s_f orm
d_nxwd/ s_nxwd
d_nxln/s_nxln
d_nxpl / s_nxp 1
320*200
4
8
160
2
640*200 640*400
2 1
screen address
4 2
160 80
2 2
Here are the 16 logical operations used in combining source and desination:
Operation
0
1
2
3
Function
D' = 0
D' = S &D
D ' = S & ~D
D' = S
Set destination to background color
Replace Mode
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4 D' = ~S & D Erase Mode
5 D' = D
6 d ' = S A D XOR Mode
7 D" = S | D
8 D' = ~ (S I D)
9 D* - ~ (S * D)
10 D ' = ~D
11 D' = S I ~D
12 D* = ~S
13 D' = ~S I D
14 D' = ~ (S & D)
15 D' = 1 Set destination to foreground color
S=Source; D -Destination range before operation; D ’ -Destination range
after the operation; &=logical AND; ! -logical OR; A=XOR (exclusive OR),
--inversion.
Four such logical operations are given for BITBLT, addressed in the
equation op = 2 * f g + bg. op is the used logical operation (0-3,
relative to optab). f g is the foreground color and bg is the background
color.
$A008 TEXTBLT
A character from any desired text font can be printed at any graphic position
with the TEXT BLock Transfer function. In addition, the form of the
character can be changed. The character can be displayed in italics,
boldface, outlines, enlarged, or rotated. These things c^not be achieved
with the "normal” character outputs via the BIOS or GEMDOS. TXTBL1
often stands as the basic structure of all text output under VD1
(v_gtext,etc.).
For the correct use of this function, a large number of parameters must be
set and controlled. A rather complicated program must be written in order to
output text with this function. If the additional options are not absolutely
necessary, it is advisable not to use this function. But decide for yourself.
Before we produce a character on the screen, we must first concern
ourselves with the organization of the fonts. We must take an especially
close look at the font header because the font is described in detail by the
information contained in it.
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A font basically consists of four sets of data: font header, font data,
character offset table and horizontal offset table. The font header contains
general data about the font, such as its name and size, the number of
characters it contains, and various other aspects. This information takes up a
total of 88 bytes. The font data contains the bit pattern of the existing
display able characters. These data are organized to save as much space as
possible.
In order to be able to better describe the organization, we will imagine a font
with only two characters, such as "A" and "B". These characters are to be
displayed in a 9x9 matrix. The font data are now in memory so that the bit
pattern of the top scan line of the "A" is stored starting at a word boundary.
Since our font is 9 pixels = 9 bits wide, one byte is completely used, but
only the top bit of the following byte. 7 bits must be wasted if the top scan
line of the "B" is also to begin on a word boundary. This is not so,
however, and the first scan line of the "B” starts with bit 6 of the second
byte of the font data. Only the data of the second and further scan lines
always start on a word boundary. In this manner, almost no bits are wasted
in the font. Only the start of the scan lines of the first character actually
begin on a word boundary; all other scan lines can begin at any bit position.
Because of this space-saving storage, the position of each character within
the font must be calculated. The calculation of the scan-line positions is
possible through the character offset table. This table contains one entry for
each displayable character. For our example, such a table would contain the
entries $0000, $0009, $0012. Through the direction of this table, it is
possible to create true proportional type on the screen since the width of
each character can be calculated. One subtracts the entry of the character to
be displayed from the entry of the next character. The last entry is present so
that the width of the last character can also be determined, although it is not
assigned to a character.
In addition to the character offset table there is the horizontal offset table.
This table is not used by most of the fonts, however. The fonts present in
the ST do not use all the possibilities of this table either. If this table were
present, it would contain a positive or negative offset value for each
character, in order to shift the character to the right or left during output.
At the end of the description of the font construction are the meanings of the
variables in the font header.
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Bytes 0- 1
Bytes 2- 3
Bytes 4-35
Bytes 36-37
Bytes 38-39
Bytes 40-49
Bytes 50-51
Bytes 52-53
Bytes 54-55
Bytes 56-57
Bytes 58-59
Bytes 60-61
Bytes 62-63
Bytes 64-65
Bytes 66-67
Byte3 68-71
Bytes 72-75
: Font identifier. A number which describes the
font . l=system font
: Font size in points (point is a measure used
in typesetting) .
: The name of the font as an ASCII string.
: Lowest ASCII value of displayable characters.
: Highest ASCII value of displayable characters.
: Relative distances of top, ascent, half,
descent, and bottom line from the base line.
: Width of the broadest character in the font.
: Width of the broadest character cell. The cell
is always at least one pixel wider than the
actual character so that two characters next
to each other are separated from each other.
: Linker offset .
: Right offset. The two offset values are used
for displaying the font in italics (skewing) .
: Thickening. If a character is to be displayed
in boldface, this variable is used.
: Underline. Contains line height in pixels.
: Lightening mask. "Light" characters are found
on the desktop when an option on a pull-down
menu is unavailable. This light grey character
consists of masking the bits with the
lightening mask. Usually the value is $5555.
: Skewing mask. As before, only for displaying
characters in italics.
: Flag. Bit 0 is set if a system font is used.
Bit 1 must be set if the horizontal offset
table is present.
Bit 2 is the so-called byte-swap flag. If it
is set, the bytes in memory are in 68000
format (low byte-high byte) . A cleared swap
flag signals that the data is in INTEL format,
reversed in memory. With this bit the fonts
from the IBM version of GEM can be used on the
ST and vice versa.
Bit 3 is set if the width of all characters in
the font is equal.
: Pointer to the horizontal offset table or
zero .
: Pointer to the character offset table.
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Bytes 76-79
Bytes 80-81
Bytes 82-83
Bytes 84-87
: Pointer to the font data.
: Form width. This variable contains the sum of
widths of all the characters. The value
represents the length of the scan lines of all
of the characters and thereby the start of the
next line .
: Form height. This variable contains the number
of scan lines for this font.
: Contain a pointer to the next font.
After so much talk, we should now list the parameters which must be noted
or prepared for the $A008 opcode.
WRT_MODE
TEXT_FG
TEXT_BG
FBASE
FWIDTH
SOURCEX
SOURCEY
DESTX
DESTY
DELX
DELY
STYLE
LITEMASK
SKEWMASK
WEIGHT
_R_OFF
_L_OFF
SCALE
_XACC_DDA
_DDA_INC
_T_SCLSTS
~CHUP
_MONO_S T ATU S
_scrtchp
_scrpt2
Write mode
Text foreground color
Text background color
Pointer to the start of the font data
Width of the font
X-coordinate of the char in the font
Y-coordinate of the char in the font
X-coordinate of the char on the screen
Y-coordinate of the char on the screen
Width of the character in pixels
Height of the character in pixels
Bit-wise coded flag for special effects
Bit pattern used for "lightening"
Bit pattern used for skewing
Factor for character enlargement
Right offset of the char for skewing
Left offset of the char for skewing
Flag for scaling
Accumulator for scaling
Scaling factor
Scaling direction flag
Character rotation vector
Flag for monospaced type
Pointer to buffer for effects
Offset scaling buffer in _scrtchp
As you can see, an enormous number of variables are evaluated for the
output of graphic text. Here we can go into only the essential (and those we
explored) variables.
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The write mode allows the output of characters in the four known modes,
replace, OR, XOR, and inverse OR. The variable text fg is in
connection with first four write modes. They form the foreground color
used for display. The background color _text_bg plays a role only with the
16 additional modes. It is clear that the additional modes are relevant only in
connection with a color screen.
The variables fbase and fwidth are set according to the desired font.
You can find the start of the font data from the header of the desired font
(bytes 76-79 in the header). _fwidth must be loaded with the contents of
the bytes 80 and 81 of the header.
The parameter sourcex determines which character you output. It should
contain the ASCII value of the desired character. The parameter sourcey
is usually zero because the character is to be generated from the top to the
bottom scan line.
The parameter jdelx can be calculated as the width of the character in
which the entry in the character offset table of the desired character is
subtracted from the next entry. The result is the width of the character in
pixels, dely must be loaded with the value of byte 82-83 of the header.
The style is something special. Here you can specify if characters should
be displayed normally or changed. The possible changes are boldface
(thicken, bit 0), shading (lighten, bit 1), italic (bit 2), and outline (bit 4).
The given change is enabled by setting the corresponding bit. Another
change is scaling. The size of a character can be changed through scaling.
Unfortunately, characters can only be enlarged on the ST.
If the scaling flag is cleared (zero), the character is displayed in its original
size. The t sclsts flag determines if the font is to be reduced or
enlarged. A value other than zero must be placed here for enlarging.
DDA iNC should contain the value of the enlargement or reduction. An
enlargement could be produced only with a value of $FFFF.
Another interesting variable is _chup. With the help of this variable,
characters can be rotated on the screen. The angle must be given in the range
0 to 360 degrees in tenths of a degree. A restriction must also be made for
this function. Usable results are obtainable only with rotations by 90
degrees. The values are $0000 for normal, $0384 for 90-degree rotation,
$0708 (upside-down type), and $0A8C for 270 degrees.
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To work with the effects, _scrchp must contain a pointer to a buffer in
which TEXTBLT can store temporary values. The exact size of this buffer
is not known, but we always found a buffer of IK to be sufficient. Another
buffer must be specified for enlargement (_scrpt2). An offset is passed as
a parameter which refers to the start of the _scrtchp buffer. A value of $40
proved to be sufficient here.
$A009 SHOW MOUSE
Calling this opcode enables the display of the mouse cursor. The cursor
follows the mouse when it is moved. If the mouse cursor is disabled, the
mouse can be used in programs which abandon the user interface GEM.
This option is particularly useful for games.
The parameters required are passed in the intin and contri arrays.
Contri (l) should be cleared before the call and contri (3) set to one.
intin (0) has a special significance. The routine for managing the mouse
cursor counts the number of calls to remove and enable the cursor. If the
cursor is disabled twice, two calls must be made to re-enable it before it will
actually appear on the screen. This behavior can be changed by clearing
intin ( o ) . With this parameter the cursor is immediately set independent of
the number of previous HIDE CURSOR calls. If the value in intin ( o ) is
not equal to zero the actually required number of $A009 calls must be made
in order to make the cursor visible.
$A00A HIDE CURSOR
This functions hides the cursor. If this function is called repeatedly, the
number is recorded by the operating system and determines the number of
calls of SHOW CURSOR before the cursor actually appears.
$A00B TRANSFORM MOUSE
Is the arrow unsuited as a mouse cursor for games? Simply make your own
cursor. How would it be if a little car moved across the screen instead of an
arrow? The opcode $A00B gives your fantasy free reign, at least as far as it
concerns the mouse cursor.
The parameters must be passed in the intin array. A total of 34 words are
necessary. The following table lists the uses and possible values:
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Intin (3) Mask color index, normally 0
Intin (4) Data color index, normally 1
Intin (5) to Intin (20) contain 16 words of the cursor mask
Intin (21) to Intin (36) contain 16 words of cursor data
The form of the cursor is determined by the cursor data. Each 1 in the data
creates a point on the screen. If a cursor is placed over a letter or pattern on
the screen, the border between the cursor and the background cannot be
determined. The mask enters at this point. Each set bit in the mask clears the
background at the given location. This draws a light border around the
cursor. Look at the normal cursor in order to see the operation of the mask.
$A00C UNDRAW SPRITE
This opcode is related to $A00D, DRAW SPRITE. The ST actually has no
hardware sprites like the Commodore 64. ST sprites are organized purely in
software. Each sprite is 16x16 pixels large. One example of an ST sprite is
the mouse cursor. It is created with this function.
To clear a previously-drawn sprite, the address of a buffer in which the
background was saved when the sprite was drawn is passed in register A2.
The opcode simply transfers the contents of the background buffer to the
right spot on the screen. The buffer itself must be 64 bytes large for each
plane. Another 10 bytes are used, independent of the number of planes. For
monochrome display, the buffer is a total of 74 bytes long, while in the
320x200 pixel resolution (for planes), it is 4x64+10=266 bytes large.
$A00D DRAW SPRITE
This function draws the desired sprite on the screen. Parameters must be
passed in the DO, Dl, A0, and A2 registers.
DO and Dl contain the X and Y-coordinates of the position of the sprite on
the screen, called the hot spot. A0 is a pointer to the so-called sprite
definition block and A2 contains the address of the sprite buffer in which
the background will be saved for erasing the sprite later.
The sprite definition block must have the following construction:
Word 1 : X offset to hot spot
Word 2 : Y offset to hot spot
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Word 3 : Format flag 0=VDI format, l=XOR format
Word 4 : Background color (bg)
Word 5 : Foreground color (fg)
Following this are 32 words which contain the sprite pattern. The pattern
must be in memory in the following order:
Word 6 : Background pattern of the top line
Word 7 : Foreground pattern of the top line
Word 8 : Background pattern of the second line
Word 9 : Foreground pattern of the second line
etc .
The information in the format flag has the following significance:
VDI Format
fg bg Result
0 0 The background appears
0 1 The color in word 4 appears
1 0 The color in word 5 appears
1 1 The color in word 5 appears
XOR Format
fg bg Result
0 0 The background appears
0 1 The color in word 4 appears
1 0 Th fb bit XORs the pixel on the screen
1 1 The color in word 5 appears
$A00E COPY RASTER FORM
Arbitrary areas of the screen can be copied with the $A00E opcode. Not
only areas within the screen, but also from the screen into free RAM, and
even more important, from the RAM to the screen. Even complete screen
pages can be copied very quickly with the COPY RASTER opcode. The
name RASTER FORM does express one limitation of the function,
however. Each raster form to be copied must begin on a word boundary and
must be a set of words.
The parameters are quite numerous and are passed in the contri, Ptsin,
and intin arrays. In addition, two "memory form definition" blocks must
be in memory for COPY RASTER. We will start with the MFD blocks.
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Since a copy operation must always have a source and a destination, one
block describes the source memory range and the second describes the
destination. Each block consists of 10 words. The address of the memory
described by the block is contained in the first two words. The third word
specifies the height of the form in pixels. Word 4 determines the width of
the form in words. Word 6 should be set to 1 and word 7 specifies the
number of planes of which the form is composed. The remaining words
should be set to zero because they are reserved for future extensions.
Necessary parameters for COPY RASTER:
INTIN [0] Bit 0-3
Opaque : Logical operation; Transparent:
Writing mode (see $A007, BITBLT)
Bit 4=0: no pattern used;
= 1 : pattern used
INTIN [1] Transparent only: 1 bit color index
INTIN [2] Transparent only: 0 bit color index
PTSIN [ 0 ] Upper left source X-coordinate
PTSIN [ 1] Upper left source Y-coordinate
PTSIN [2] Lower right source X-coordinate
PTSIN [3] Lower right source Y-coordinate
PTSIN [4] Upper left destination X-coordinate
PTSIN [5] Upper left destination Y-coordinate
PTSIN [6] Lower right destination X-coordinate
PTSIN [7] Lower right destination Y-coordinate
CONTRL [7+8] Address source MFDB
CONTRL[9+10] Address destination MFDB
_patptr Pattern pointer (when used)
_multifill 0 = pattern has one plane
1 = pattern has several planes
_COPYTRAN 0 = opaque
N-plane source and n-plane destination
1 = transparent
Source with a plane copied through all
destination planes (transparent) .
Memory Form Definition Block (MFDB) design:
Offset Size Meaning
0 long Pointer to raster image
4 word Raster width in pixels
6 word Raster height in pixels
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8 word Raster width in words
10 word Format flag
0 = device-specific
1 = number of bit planes
12 word Number of bit planes
14 word Reserved
When the COPY RASTER function is used, the raster image in
device-specific format must be laid out first. (Standard format arranges the
bitplanes one after the other, instead of nesting them by words).
A few remarks about the words "opaque" and "transparent:" Opaque
copying simply combines the corresponding color planes of source and
destination, as well as the resulting raster, though a logical operation with a
value from 0 to 15 (see also $A007, BITBLT). Here the number of color
planes in source and destination must match, or else the function stops.
Opaque copying doesn't require the values in INTIN[1] and INTIN[2].
Transparent copying copies a source range containing a single color plane to
a multicolor destination range. The source range consists of only two
different colors, represented by bits 0 and 1. You can determine which color
appears in the source range pixels. Give the corresponding color numbers in
INTIN[1J and INTIN[2].
In INTIN[0] writing mode is used instead of the logical operations:
INTIN [0]
1
2
3
4
Writing mode
Replace mode
Transparent mode
XOR mode
Reverse transparent mode
These procedures serve when a source range is only two colors, and when a
monochrome as well as a color screen are used. Monochrome copying
naturally displays in black and white; color screens can use the two colors
from the available palette. The diskette icons from the Desktop are copied
using these procedures.
Copy Raster Opaque is identical in the other respects to the VDI function
109, vro_cpyfm, while Copy Raster Transparent corresponds to the VDI
function 121, vrt cpyfm.
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$A00F CONTOUR FILL (FLOOD FILL)
The line- A opcode $A00F is not documented by Atari at present. However,
when you look at the program with the help of a disassembler, you can see
a $A00x opcode execute. It’s much more difficult to determine WHICH
function the $A00F opcode performs. Now, this is our mystery to be
unraveled. $A00F calls a fill routine. This fill is identical to the VDI
function 103 Contour Fill.
Contour Fill requires an XY coordinate and a mode word for parameters.
The coordinates are stored in PTSIN(O) and PTSIN(l), the mode word in
INTIN(O). The mode word means the following: If we have a positive
value, this value is established as the color value. An area is then filled with
either the border color or the given color. If the value is negative, the fill is
limited to the color of the starting point.
Some of the variables important to this command are clipping, write mode,
pattern pointer and pattern mask without multifill.
3.4.1 An overview of the "line-A" variables
After the initialization $A000, DO and AO contain the address of a variable
area which contains more than 50 line-A variables. The essential variables
have been described along with the various calls, but not the location of the
variables within the variable block. We will present this list shortly. When
naming the variables we have remained with the names used in the official
Atari documentation.
Offset is the value which must be given to access the value register relative.
Variables supplied with a question mark could not be definitively explained.
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Offset
Name
Size
0
v_planes
word
2
v_lin wr
word
4
Contrl
long
8
Intin
long
12
Ptsin
long
16
Intout
long
20
Ptsout
long
24
_FG_BP_1
word
26
_FG_BP_2
word
28
_FG_BP_3
word
30
_FG_BP_4
word
32
_LSTLIN
word
34
_LN_MASK
word
36
_WRT_MODE
word
38
_X1
word
40
_Y1
word
42
_X2
word
44
_Y2
word
46
_patptr
long
50
_patmsk
word
52
_multif ill
word
54
_CLIP
word
56
_XMN_CLIP
word
58
_YMN_CLIP
word
60
_XMX_CLIP
word
62
_YMX_CLIP
word
64
_XACC_DDA
word
66
DDA INC
word
68 T SCLSTS word
Function
Number of planes
Bytes per scan line
Pointer to the Contrl array
Pointer to the Intin array
Pointer to the Ptsin array
Pointer to the Intout array
Pointer to the Ptsout array
Plane 0 color value
Plane 1 color value
Plane 2 color value
Plane 3 color value
Should be -1 ( $FFFF) (?)
Line pattern for $A003
Write mode (0=write mode
l=transparent
2=X0R mode
3=Inverse trans.)
Xl-coordinate
Yl-coordinate
X2-coordinate
Y2-coordinate
Fill pattern pointer
(see $A004)
Fill pattern "mask"
(see $A004)
0=fill pattern for one plane
l=fill pattern for multiplane
0=no clipping (see $A005)
unequal to 0=clipping
define upper left corner of
the visible clipping area and
define lower right corner of
the visible area for clipping
Should be set to $8000 before
each call to TXTBLT (?)
Enlargement/reduction factor
$FFFF for enlargement,
reduction doesn't work (?)
0=reduction (?)
l=enlargement
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70 _MONO_S T ATU S word l=no proportional font
0=proportional type or width
of character changed by bold
or italics
72 _SOURCEX word X-coordinate of char in font
7 4 _SOURCEY word Y-coord of char in font (0)
Note: SOURCEX is the value of the character from the
horizontal offset table (HOT) and can be calculated with
the formula SOURCEX = HOT-element (ASCII value minus
FIRST ADE) . The variable FIRST ADE is contained in bytes
36,37 of the font header (see example)
76
_DESTX
word
X-position of char on screen
78
_DESTY
word
Y-position of char on screen
80
_DELX
word
Character width
82
JDELY
word
Character height
Note :
DELX can be calculated with the formula DELX =
SOURCE X+l minus SOURCEX (see $A008) . DELY is the value
FORM
height from bytes 82,
83 of the font header.
84
__FBASE
long
Pointer to start of font data
88
_FWIDTH
long
Width of font form
90
_STYLE
word
Special effects flag
(see $A008)
92
_LITEMASK
word
Mask for shading
94
_SKEWMASK
word
Mask for italic type
96
_WEIGHT
word
Number of bits by which the
character will be expanded
98
_R_OFF
word
Offset for italic type
100
_L_OFF
word
Offset for italic type
Note
: The above five
variables should be loaded with the
corresponding values
from
the font header.
102
_SCALE
word
Q=no scaling
l=scaling (enlarge/reduce)
104
_CHUP
word
Angle for character rotation
0=normal char representation
$384=rotated 90 degrees
$708=rotated 180 degrees
$A8C=rotated 270 degrees
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106
_TEXT_FG
word
Text display foreground color
108
_scrtchp
long
Buffer address required for
creating special text effects
112
_scrpt2
word
Offset of the enlargement
buffer in the scrtchp buffer
114
_TEXT_BG
word
Background color for text rep
116
_COPYTRAN
word
(?)
3.4.2 Examples for using the line-A opcodes
To make your first experiments with the line-A opcodes easier, here are a
few examples to serve you as a starting point. In the first example, $A001
sets a point is set on the screen with $A001, $A002 sets the point’s color.
* Demo of $AOOO,$AOQ1 and $A002 functions
Intin
equ
8
Ptsin
equ
12
init
equ
$a000
setpix
equ
$a001
getpix
equ
$a002
start :
. dc . w
init
call $A000
move . 1
Intin (aO) , a3
address of Intin-arrays
move . 1
Ptsin (aO) , a4
address of Ptsin-arrays
move
#300, <a4)
X coordinate
move
#100,2 <a4)
Y coordinate
move
#1, <a3)
color set, pixel set
0 erases pixel
. dc . w
setpix
set pixel
move
#300, <a4)
X coordinate
move
#100,2 <a4)
y coordinate
. dc . w
getpix
get color value
dO now contains color value
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A monochrome monitor requires only the color values zero and one. Other
values can be entered when working in one of the color modes, however.
The next example shows how a triangle can be drawn on the screen with the
function FILLED POLYGON.
*************************************************
* a006 - filled polygon
*************************************************
contr 1
equ
4
ptsin
equ
12
fg bpl
equ
24
fg_bp2
equ
26
f g_bp3
equ
28
fg_bp4
equ
30
wrt mod
equ
36
yi
equ
40
patptr
equ
46
patmsk
equ
50
multifill
equ
52
clip
equ
54
xmn_clip
equ
56
ymn_clip
equ
58
xmx clip
equ
60
ymx_clip
equ
62
init
equ
$a000
polygon
equ
$a006
.dc. w
init
get variable block address
from AO
move . w
#1, fg_bpl (aO)
set colors for
clr . w
fg bp2 (aO)
monochrome only
clr . w
fg bp3 (aO)
clr . w
fg_bp4 (aO)
move . w
#2, wrt mod(aO)
replace mode
move . 1
#fill, patptr (aO)
pointer to the fill pattern
move . w
#4, patmsk (aO)
four fill patterns
clr . w
multifill (aO)
only one plane (monochrome)
clr . w
clip(aO)
no clipping
move . 1
contrl (aO) , a6
Contrl array address from A6
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addq . 1
#2,a6
A6 > Contrl (1)
move . w
#3, ( a 6 )
the XY pair in Ptsin
move . 1
ptsin (aO) , a6
Ptsin array address from A6
move . 1
#tab, a5
Coordinate table
move . w
#8,d3
receive 8 coordinates
loop
move . w
(a5) +, (a6) +
dbra
d3, loop
move . w
#100, d3
first scanline
loopl
move . w
d3, yl (aO)
from Yl
move . 1
aO, - (sp)
store address variable block
dc.w
polygon
fill scanline, destroy A0
move . 1
(sp) +, aO
restore A0
addq . w
#1 , d3
calculate next scanline
cmp.w
#301, d3
last scanline?
bne
loopl
no, next scanline
rts
subroutine all done
fill:
dc.w
%1100110011001100
dc.w
%0110110110110110
dc.w
%0011001100110011
dc.w
*1001100110011001
tab:
dc.w
320,100
dc.w
120, 300
dc.w
520,300
dc.w
320,100
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The next example shows how to enable the mouse and manipulate the
cursor form. The example waits for a key press before returning.
********************************************************
★
show mouse - transform
mouse
*********************
***********************************
intin
equ
8
init_a
equ
$a000
show__mouse
equ
$a009
transmouse
equ
$a00b
start :
.dc.w
init_a
address Intin from A5
move . 1
Intin (aO) , a5
move
#0, 6<a5)
Intin (3) = mask color value
move
#1, 8 (a5)
Intin (4) = data color value
add. 1
#10, a5
a5 > Intin (5)
lea
maus, a4
data for new cursor
move
#15, dO
32 words = 16 longs
loop:
move . 1
(a4) +, (a5) +
transfer Intin array
dbra
dO, loop
.dc.w
transmouse
and set form
.dc.w
init_a
move . 1
Intin (aO) , aO
clr .w
(aO)
Number Hide Cursor -ignore call
.dc.w
show mouse
now the new cursor
rts
subroutine all done
maus :
maske :
.dc.w %0000000110000000
.dc.w %0000011111100000
.dc.w %0001111111111000
.dc.w %0111111111111110
.dc.w
.dc.w %1111001111001111
.dc.w %1111001111001111
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.dc.w
. dc . w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
daten :
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
.dc.w
%1111001111001111
%0000001111000000
%0000001111000000
%0000001111000000
%0000001111000000
%0000001111000000
%0000001111000000
%0000000000000000
%0000000000000000
%0000000000000000
%0000000110000000
%0000011001100000
%0110000110000110
%0110000110000110
%0000000110000000
%0000000110000000
%0000000110000000
%0000000110000000
%0000000110000000
%0000000110000000
%0000000110000000
%0000000000000000
%0000000000000000
234
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3.5 The Exception Vectors
The first 1024 bytes of the 68000 processor are reserved for the exception
vectors. Routines which use exception handling store the addresses they
require in this range of memory.
A condition which leads to an exception can come either from the processor
itself or from the peripheral components and controls units connected to it.
The interrupts, described in the next section, belong to the class of external
events. In addition, a so-called bus error can be created externally.
A bus error can be created by many circumstances. For one, certain memory
areas can be protected from unauthorized access by it. As you may already
know, the 68000 can run in one of two operating modes. The operating
system is driven at the first level, the supervisor mode. The user mode is
intended for user programs. In order that a user program not be able to
access important system variables as well as the system components in an
uncontrolled fashion, such an access in the user mode leads to a bus error.
If such an error occurs, the processor stops execution of the instruction,
saves the program counter and status register on the stack, and branches to a
routine, the address of which it fetches from the lowest 1024 bytes of
memory. In the case of the bus error, the address is at memory location 8
(one long word). What happens in this routine?
First the vector number of the interrupt is determined and placed in address
$3C4. Then the registers will get up to 16 words from the system stack and
store them. Therein is the address by which the interruption occurred, as
well as the current system status. In the case of a bus or address error,
these words contain the address at which the error occurred, as well as the
type of access (see any 68000 user's manual). As many cherry bombs
appear on the screen as the interrupt vector number. In the case of a bus
error, for example, this number is 2. Execution then returns to the GEM
Desktop.
The range in which the above information will be stored retains this
information until the ST is reset. It therefore conveys the complete status of
the processor until a crash occurs. The data lie at the following addresses.
$380 contains $12345678 when the following data is valid
$384 - $3 A3 DO - D7
$3A4 - $3BF AO - A6
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$3C0
SSP
$3C4
Exception
number
$3C8
USP
$3CC - $3EB
16 words
from SSP
The following table contains all of the exception vectors.
Vector number
Address
Exception vector meaning
0
$000
Stack pointer after reset
1
$004
Program counter after reset
2
$008
Bus error
3
$00C
Address error
4
$010
Illegal instruction
5
$014
Division by zero
6
$018
CHK instruction
7
$01C
TRAPV instruction
8
$020
Privilege violation
9
$024
Trace
10
$028
Line-A emulator
11
$02C
Line-F emulator
12-14
$030~$038
reserved
15
$03C
Uninitialized interrupt
16-23
$040-$05C
reserved
24
$060
Spurious interrupt
25
$064
Level 1 interrupt
26
$068
Level 2 interrupt
27
$0 6C
Level 3 interrupt
28
$070
Level 4 interrupt
29
$074
Level 5 interrupt
30
$078
Level 6 interrupt
31
$07C
Level 7 interrupt
32
$080
TRAP #0 instruction
33
$084
TRAP #1 instruction
34
$088
TRAP #2 instruction
35
$08C
TRAP #3 instruction
36
$090
TRAP #4 instruction
37
$094
TRAP #5 instruction
38
$098
TRAP #6 instruction
39
$0 9C
TRAP #7 instruction
40
$0A0
TRAP #8 instruction
41
$0A4
TRAP #9 instruction
42
$0A8
TRAP #10 instruction
43
$0AC
TRAP #11 instruction
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Abacus Software
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44
$0B0
TRAP
#12
instruction
45
$0B4
TRAP
#13
instruction
46
$0B8
TRAP
#14
instruction
47
$0BC
TRAP
#15
instruction
48-63
64-255
$0C0-$0FC
$100-$3FC
reserved
User interrupt vectors
The following vectors are used on the ST:
Line-A emulator
Line-F emulator
Level 2 interrupt
Level 4 interrupt
TRAP #1 GEMDOS
TRAP #2 GEM
TRAP #13 BIOS
TRAP #14 XBIOS
$FC9CA2 / $FB30
$A30E / $3A6AE
$FC0 61E / $64AC
$FC0 634 / $64C2
$FC4D4 8 / $ABD6
$FE340E / $29B7 6
$FC074E / $65DC
$FC0748 / $65D6
The first address refers to the ROM version; the second address is read
when the operating system is found in RAM. The vector for division by
zero points to rte and returns directly to the interrupted program. Vectors
64-79 are reserved for the MFP 68901 interrupts. All other vectors point to
$FC0A1A/$68A8 which outputs the vector number and ends the program as
described for the bus error.
All of the unused vectors can be used for your own purposes, such as the
line-F emulator or the 12 unused traps.
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3.5.1 The line-F emulator
The ST operating system uses the line-F emulator to replace frequently used
command sequences with just one command. Since the better part of the
operating system is written in C, especially the AES, you'll often find a
sequence at the end of a C subroutine, generated by the compiler:
tst.l (A7)+
movem.l (A7) +, Dx-Dy/Ax-Ay
unlk A6
rts
This sequence requires 5 words. A 16-bit mask in the movem command
decides which register will be taken from the stack. Bits 0 - 7 stand for data
registers DO - D7, and bits 8 - 15 are for the address registers (AO - A7).
This mask is ORed by the opcode $F000 to shift the second bit to the right,
and set bit 0. Thus it is possible to get the register contents of D3 - D7 and
AO - A5, which are used by the C compiler, from the stack. Four words
will be stored during this procedure.
If bit 0 is not set in the line-F command, the opcode will be interpreted as a
pointer in a table, from which the address of a routine will be taken. This
routine will then branch to the return address previously placed on the stack.
The opcode must be divisible by 4; e.g., $F000, $F004, etc., up to $F9CC.
The jump table resides at $FEE8BC-$FEF28B or $34B60-$3552F.
Since the line-F routine contains self-modifying code, it is copied into
RAM.
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00A30E
34 IF
move .w
(A7) +,D2
Get status from stack
00A310
205F
move . 1
(A7) +, A0
Return address
00A312
3218
move . w
(A0) + ,D1
Get opcode
OOA314
08010000
btst
#0 , D1
Bit 0 set?
00A318
6614
bne
$A32E
Yes
00A31A
4 6C2
move . w
D2 , SR
Set status
00A31C
2F08
move . 1
A0,- (A7)
Return addr . from stack
00A31E
02410FFF
and.w
#$0FFF,D1
Delete bits 12-15
00A322
207C00FEE8BC
move . 1
#$FEE8BC, A0
Base address of table
00A328
20701000
move . 1
0 (A0,D1.W) , A0
Get address
00A32C
4ED0
jmp
(A0)
Execute routine
00A32E
02410FFE
and.w
#$0FFE,D1
Delete bits 12-15 and bit
00A332
6712
beq
$A34 6
$F001 , then unlk/rts
00A334
E54 9
lsl . w
#2 , D1
Shift mask
00A336
007C07000
or .w
#$700, SR
Save IPL 7, interrupts
00A33A
41FA0008
lea
$A34 4 (PC) ,A0
Register mask address
00A33E
3081
move .w
Dl, (A0)
Copy mask in program
00A340
588F
addq . 1
#4 , A7
Correct stack
00A342
4CDF2000
movem. 1
(A7) + , A5
Get register again
00A346
4 6C2
move .w
D2 , SR
Set status
00A348
OOA34A
4E5E
4E75
unlk
rts
Bit no.
A 6 release local variables
Return from call
: FEDCBA987 654 3210
Opcode : 1111XXXXXXXXXXX1
Register : AAAAAADDDDD
54321076543
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3.5.2 The interrupt structure of the ST
The interrupt capabilities offered by the 68000 microprocessor are put to
good use in the ST. As you may have already gathered from the hardware
description of the processor, the processor has seven interrupt levels with
different priorities. The interrupt mask in the system byte of the status
register determines which levels can generate an interrupt. An interrupt can
only be generated by a level higher than the current contents of the mask in
the status register. A interrupt of a certain priority is communicated to the
processor by the three interrupt priority level inputs. The following
assignment results:
Level IPL 210
7 (NMI) 000
6 0 0 1
5 0 10
4 011
3 10 0
2 10 1
1 110
0 111
If all three lines are 1 (interrupt level 0), no interrupt is present. Interrupt
level 7 is the NMI (non-maskable interrupt), which is executed even if the
interrupt mask in the status register contains seven. Which interrupt is
assigned which vector (that is, the address of the routine which will process
the interrupt) depends on the peripheral component which generates the
interrupt. For auto-vectors, the processor itself derives the interrupt number
from the interrupt level. The following table is used in this process:
Level
Vector number
Vector address
IPL 1
25
$64
IPL 2
26
$68
IPL 3
27
$6C
IPL 4
28
$70
IPL 5
29
$74
IPL 6
30
$78
IPL 7
31
$7C
Only lines IPL 1 and IPL 2 are used on the Atari ST; Line IPL is
permanently set to a 1 level so that only levels 2, 4 and 6 are available. The
results in the following assignment:
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IPL 2 HBL, horizontal blank, line return
IPL 4 VBL, vertical blank, picture return
IPL 6 MFP 68901
The HPL interrupt is generated on each line return from the video section. It
is generated every 50 to 64 (is depending on the monitor connected
(monochrome or color). It occurs very often and is normally not permitted
by an interrupt mask of three. The standard HBL routine therefore only has
the task of setting the interrupt mask to three if it is zero and allows the HBL
interrupt so that no more HBL interrupts will occur. One use of the HBL
interrupt could be for special screen effects. With the help of this routine,
you know exactly which line of the screen has just been displayed. Of much
greater importance, however, is the VBL interrupt, which is generated on
each picture return. This occurs 50, 60, or 70 times per second depending
on the monitor.
The vertical blank interrupt (VBL) routine accomplishes a whole set of a
tasks which must be periodically executed or which concern the screen
display. When entering the routine, the frame counter _f r clock ($466) is
first incremented. Next, a test is made to see if the VBL interrupt is
software-disabled. This is the case if vblsem ($452) (vertical blank
semaphore) is zero or negative. In this case the routine is exited immediately
and execution returns to the interrupted program. Otherwise, all of the
registers are saved on the stack and the counter vbclock ($462), which
counts the executed VBL routines, is incremented. Next, a check is made to
see if a different monitor has been connected in the meantime. If a change
was made from a monochrome to color monitor, the video shifter is
reprogrammed accordingly. This is necessary because the high screen
frequency of 70 Hz of the monochrome monitor could damage a color
monitor. The routine to flash the cursor is called next. If you load a new
color palette via the appropriate BIOS functions or want to change the
screen address, this happens here in the VBL routine. Since nothing is
displayed at this time, a change can be made here without disturbing
anything else. If colorptr ($45 A) is not equal to zero, it is interpreted as
a pointer to a new color palette, and this is loaded into the video shifter. The
pointer is then cleared again. If screenpt r is set, this value is used as the
new base address of the screen. This takes care of the screen specific
portions.
Now the floppy VBL routine is called which, with the help of the write
protect status, determines if a diskette was changed. An additional task of
this routine is to deselect the drives after the disk controller has turned the
drive motor off.
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Now comes the most interesting part for the programmer, the processing of
the VBL queue. There is a way to tell the operating system to execute your
own routines within the VBL interrupt. The maximum number of routines
possible is in nvbls ($454). This value is normally initialized to 8, but it
can be increased if required. Address _vbl queue ($456) contains a
pointer to a vector array which contains the (8) addresses of the VBL
routines. Each address is tested within the VBL routine and the
corresponding routine executed if the address is not zero.
If you want to install your own VBL routine, check the 8 entries until you
find one which contains a zero. At this address you can write a pointer to
your routine which from now on will be executed in every VBL interrupt.
In all 8 entries are already occupied, you can copy the entries into a free area
of memory, append the address of your routine, and redirect __vbl queue
to point to the new vector array. Naturally, you must not forget to increment
vbls, the number of routines, correspondingly. Your routine may change
all registers with the exception of the USP.
As soon as the VBL routine is done, the _dmpf lg ($4EE) is checked. If
this memory location is zero, a hardcopy of the screen is outputted. The flag
is set in the keyboard interrupt routine if the keys ALT and HELP are
pressed at the same time. Finally, the register contents are restored,
vblsem is released and execution returns to the interrupted routine.
The MFP 68901 occupies interrupt level six in our previous table. This
component is in the position to create interrupt vectors on its own. These are
referred to non-auto vectors in contrast to the auto vectors used above,
because the processor does not generate the vector itself. In the Atari ST,
the MFP 68901 works as the interrupt controller. It manages the interrupt
requests of all peripheral components including its own.
The MFP can manage sixteen interrupts which are prioritized in reference to
each other, similar to the seven levels of the processor. All MFP interrupts
appear on level 6 to the 68000, therefore prioritized higher than HBL and
VBL interrupts. The table on the next page contains the assignments within
the MFP.
Level
Assignment
15
Monochrome monitor detect
14
RS-232
ring indicator
13
System
clock timer A
12
RS-232
receive buffer full
11
RS-232
receive error
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Level Assignment
10 RS-232 transmit buffer empty
9 RS-232 transmit error
8 Line return counter, timer B
7 Floppy controller and DMA
6 Keyboard and MIDI ACIAs
5 Timer C
4 RS-232 baud rate generator, timer D
3 unused
2 RS-232 CTS
1 RS-232 DCD
0 Centronics busy
Not all of these possible interrupt sources are enabled, however. Some
signals are processed through polling. The following is a description of the
interrupts which are used by the operating system.
Level 2, RS-232 CTS, address $FC26B2 / $8540
This interrupt is generated every time the RS-232 interface is informed via
the CTS line that a connected receiver is ready to receive additional data.
The routine then sends the next character from the RS-232 transmit buffer.
Level 5, Timer C, address $FC2F78 / $8E06
This timer runs at 200 Hz. The 200 Hz counter at $4B A is first incremented
in the interrupt routine. The next actions are performed only every fourth
call to the interrupt routine, that is, only every 20ms (50 Hz). First a routine
is called which handles the sound processing. Another task of this interrupt
is the keyboard repeat when a key is pressed and initial repeat. Finally, the
evt t imer routine of GEM is called, which is accessed via vector $400.
Level 6, Keyboard and Midi, address $FC281C / $86AA
Two peripheral components are connected to this interrupt level of the MFP,
the two ACIAs which receive data from the keyboard and the MIDI
interface. In order to decide which of the two components has requested an
interrupt, the interrupt request bits in the status registers of the ACIAs are
tested and the received byte is fetched if required. If it comes from the
keyboard, the scan code is converted to the ASCII code by means of the
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Abacus Software
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keyboard table and written into the receive buffer, which happens
immediately for MIDI data. Mouse and joystick data also come from the
keyboard ACIA and are also prepared accordingly.
Level 9, RS-232 transmit error, address $FC2718 / $85A6
If an error occurs while sending RS-232 data, this interrupt routine is
activated. Here the transmitter status register is read and the status is saved
in the RS-232 parameter block.
Level 10, RS-232 transmit buffer empty, address $FC2666 /
$84F4
Each time the MFP has completely outputted a data byte via the RS-232
interface, it generates this interrupt. It is then ready to send the next byte. If
data is still in the transmit buffer, the next byte is written into the transmit
register, which can now be shifted out according to the selected baud rate.
Level 11, RS-232 receive error, address $FC26FA / $8588
If an error occurs when receiving RS-232 data, this interrupt routine is
activated. This may involve a parity error or an overflow. The routine only
clears the receiver status register and then returns.
Level 12, RS-232 receive buffer full, address $FC2596 /
$8424
If the MFP has received a complete byte, this interrupt occurs. Here the
character can be fetched and written into the receive buffer (if there is still
room). This routine takes into account the active handshake mode (sending
XON/XOFF or RTS/CTS).
The other interrupt possibilities of the MFP are not used, but they can be
used for your own routines. For example, interrupt level 0, Centronics
strobe, can be used for buffered printer output.
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3.6 The Atari ST VT52 Emulator
There are two options for text output on the ST. You can work with the
GEMDOS functions by means of TRAP#1 or a direct BIOS call with
TRAP #13. The other possibility consists of using the VDI functions.
You have special options for screen control with both variants. We will first
take a look at output using the normal DOS or BIOS calls. Here a terminal
of type VT52, which offers a wide variety of control functions, is emulated
for screen output. These control characters are prefixed with a special
character, the escape code. Escape, or ESC for short, has an ASCII code of
27. Following the escape code is a letter which determines the function, as
well as additional parameters if required. The following list contains all of
the control codes and their significance.
ESC A Cursor up
This function moves the cursor up one line. If the cursor was already
on the top line, nothing happens.
ESC B Cursor down
This ESC sequence positions the cursor one line down. If the cursor
is already on the bottom line, nothing happens.
ESC C Cursor right
This sequence moves the cursor one column to the right.
ESC D Cursor left
Moves the cursor one position to the left. This function is identical to
the control code backspace (BS, ASCII code 8). If the cursor is
already in the first column, nothing happens.
ESC E Clear Home
This control sequence clears the entire screen and positions the cursor
in the upper left comer of the screen (home position).
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ESC H Cursor home
With this function you can place the cursor in the upper left comer of
the screen without erasing the contents of the screen.
ESC I Cursor up
This sequence moves the cursor one line towards the top. In contrast
to ESC A, however, if the cursor is already in the top line, a blank
line is inserted and the remainder of the screen is scrolled down a line
correspondingly. The column position of the cursor remains
unchanged.
ESC J Clear below cursor
By means of this function, the rest of the screen below the current
cursor position is cleared. The cursor position itself is not changed.
ESC K Clear remainder of line
This ESC sequence clears the rest of the line in which the cursor is
found. The cursor position itself is also cleared, but the position is
not changed.
ESC L Insert line
This makes it possible to insert a blank line at the current ^-rsor
position. The remainder of the screen is shifted down; the lowest line
is then lost. The cursor is placed at the start of the new line after the
insertion.
ESC M Delete line
This function clears the line in which the cursor is found and moves
the rest of the screen up one line. The lowest screen line then
becomes free. After the deletion, the cursor is moved up to the first
column of the line that takes the place of the deleted line.
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ESC Y Position cursor
This is among the most important functions. It allows the cursor to be
positioned at any place on the screen. The function needs the cursor
line and column as parameters, which are expected in this order with
an offset of 32. If you want to set the cursor to line 7, column 40,
you must output the sequence ESC Y CHR$(32+7) CHR$(32+40).
Lines and columns are counter starting at zero; for an 80x25 screen
the lines are numbered from 0 to 24 and the columns from 0 to 79.
The remaining ESC sequences of the VT52 terminal start with a lower case
letter.
ESC b Select character color
With this function you can select the character color for further
output. With a monochrome monitor you have choice between just
0=white and l=black. For color display you can select from 4 or 16
colors depending on the mode. Only the lowest four bits of the
parameters are evaluated (mod 16). You can use the digit " 1" for the
color 1 as well as the letters "A" or "a" in addition to binary one.
ESC c Select background color
This function serves to select the background color in a similar
manner. If you choose the same color for character and background,
you will, of course, not be able to see text output any more.
ESC d Clear screen to cursor position
This sequence causes the screen to be erased starting at the top and
going to the current position of the cursor, inclusive. The position of
the cursor is not changed.
ESC e Enable cursor
Through this escape sequence the cursor becomes visible. The cursor
can, for example, be enabled when waiting for input from the user.
ESC f Disable cursor
Turns the cursor off again.
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ESC j Save cursor position
If you want to save the current position of the cursor, you can use
this sequence to do so. Unfortunately, this function is also used by
other ESC sequences, so the stored value is no longer available to
you if you use some other sequences.
ESC k Set cursor to the saved position
This is the counterpart of the above function. It sets the cursor to the
position which was previously saved with ESC j. If no cursor
position was saved, the cursor will go to the home position.
ESC 1 Clear line
Clears the line in which the cursor is located. The remaining lines
remain unaffected. After the line is cleared, the cursor is located in the
first column of the line.
ESC o Clear from start
This clears the current cursor line from the start to the cursor position,
inclusive. The position of the cursor remains unchanged.
ESC p Reverse on
The reverse (inverted) output is enabled with this sequence. For all
further output, the character and background colors are exchanged. A
monochrome monitor will show white type on a black background.
ESC q Reverse off
This sequence serves to re-enable the normal character display mode.
ESC v Automatic overflow on
After executing this sequence, an attempted output beyond the end of
line will automatically start a new line.
ESC w Automatic overflow off
This deactivates the above sequence. An attempt to write beyond the
line will result in all following characters being written in the last
column.
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Similar functions are available to you under VDI. The VDI escape functions
(opcode 5) serve this purpose. The appropriate screen function is selected
by choosing the proper function number. Note, however, that under VDI
the line and column numbering does not begin with zero but with one.
Under VDI there is also a function which outputs a string at specific screen
coordinates. If necessary, you can use the ESC functions of the VT52
emulation in addition.
The output of "unprintable" control characters
The three system fonts of the ST have also been supplied with characters for
the ASCII codes zero to 31, which are normally interpreted as control
codes. On the ST, only codes 7 (BEL), 8 (BS backspace), 9 (TAB), as well
as 10, 11, and 12 (LF linefeed, VT vertical tab, and FF form feed all
generate a linefeed) plus 13 (CR carriage return) have effect, in addition to
ESC. The remaining codes have no effect. How do we access the characters
below 32?
To do this, an additional device number is provided in the BIOS function 3
"conouf '. Normally number 2 "con" serves for output to the screen. If one
selects number 5, however, all the codes from, 0 to 255 are outputted as
printable characters, control codes are no longer taken into account.
You will find the three ST system fonts pictured in the Appendix.
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3.7 The ST System Variables
The ST uses a set of system variables whose significance and addresses will
not change in future versions of the operating system. If you use other
variables, such as those from the BIOS listing which are not listed here, you
should always remember that these could have a different meaning in a new
version of the operating system. The system variables are in the lower RAM
area directly above the 68000 exception vectors, at address $400 to 1024.
The address range from 0 to $7FF (2047) can be accessed only in the
supervisor mode. An access in the user mode leads to a bus error.
In the following listing we will use the original names from Atari. In
addition to the address of the given variable, typical contents and the
significance will be described. Two values are sometimes given for one
address: The first signifies the address in the ROM version of the operating
system, while the second address refers to the operating system when in
RAM, unless stated otherwise in the text.
Address length name sample contents
$400 L etv_timer $FCA62A / $104B8
This is the GEM event timer vector. It handles periodic GEM tasks.
$404 L etv_critic $FC0744 / $65D2
Critical error handler. Under GEM this pointer points to
$FE3226/$294DE. There an attempt is made to correct disk errors,
such as if a another disk is requested in a single-drive system.
$408 L etv_term $FC05C0 / $644E
This is the GEM vector for ending a program.
$40C 5L etv_xtra
Here is space for 5 additional GEM vectors, presendy not yet used.
$420 L memvalid $752019F3
If the memory location contains the given value, the configuration of
the memory controller is valid.
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$424 W memctrl $05
This is a copy of the configuration value in the memory controller.
The value given applies for a 1MB machine.
$426 L resvalid $31415926
A given value located here causes a jump to the reset vector ($42A).
$ 42A L resvector $FC00 0 8
See above.
$42E L phystop $80000 / $100000
This is the physical end of the RAM memory; $80000 for a 512K
machine and $100000 for a 1MB machine.
$432 L _membot $A100 / $39FF0
The user memory begins here (TP A, transient program area).
$436 L _memtop $F8 0 00
This is the upper end of the user memory.
$43A L memval2 $2 37 6 98 AA
This value and "memvalid" declare the memory configuration.
$43E W flock 0
If this variable contains a value other than zero, a disk access is in
progress and the VBL disk routine is disabled.
$440 W seekrate 3
The seek rate (the time it takes to move the read/write head to the next
track) is determined according to the following table:
Seek rate Time
0 6 ms
1 12 ms
2 2 ms
3 3 ms
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$442 W _timer_ms $14, 2 0 ms
The time span between two timer calls, 20 ms corresponds to 50 Hz.
$444 W _fverify $FF
If this memory location contains a value other than zero, a verify is
performed after every disk write access.
$446 W _bootdev 0
Contains the device number of the drive from which the operating
system was loaded.
$448 W palmode 0
If this variable contains a value other than zero, the system is in the
PAL mode (50 Hz); if the value is zero, it means the NTSC mode.
$44A W defshiftmod 0
If the Atari is switched from monochrome to color, it gets the new
resolution from here (0=low, 1 medium resolution).
$44C W sshiftmd $2
Here is a copy of the register contents for the screen resolution.
0 320x200, low resolution
1 640x200, medium resolution
2 640x400, high resolution
$ 4 4E L _v_bas_ad $ F 8 0 0 0
This variable contains a pointer to video RAM (logical screen base).
The screen address must always begin on a 256 byte boundary.
$452 W vblsem 1
If this variable is zero, the vertical blank routine is not executed.
$454 W nvbls 8
Number of vertical blank routines.
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$456 L _vblqueue $4CE
Pointer to a list of nvbls routines which will be executed during the
VBL.
$45A L colorptr 0
If this value is not zero, it is interpreted as a pointer to a color palette
which will be loaded at the next VBL.
$45E L screenpt 0
This is a pointer to the start of the video RAM, which will be set
during the next VBL (zero if no new address is to be set).
$462 L _vbclock $2D2 6A
Counter for the number of VBL interrupts.
$466 L _f rclock $2D267
Number of VBL routines executed (not disabled by vblsem).
$4 6A L hdv_init $FC0D60 / $ 6BEE
Vector for hard disk initialization.
$46E L swv_vec $FC0020 / $6120
Vector for monitor change. A branch is made through this vector
when another monitor (color/monochrome) is connected (default is
reset).
$472 L hdvjbpb $FC0DE6 / $6C7 4
Vector to get the parameter block for a hard disk (BIOS function 7).
$476 L hdv_rw $FC10D2 / $6F60
Read/write routine vector for a hard disk (BIOS function 4).
$47A L hdvjDOOt $FC137C / $720A
Vector for loading a boot sector.
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$47E L hdv_mediach $FC0F9 6 / $6E2 4
Media change routine vector for hard disk (BIOS function 9).
$482 W _cmdload 0
If the boot program sets this variable to a value other than zero, the
ST attempts to load a program called "COMMAND.PRG" once the
operating system loads (e.g. an application other than the Desktop).
$484 B content! 6
Attribute vector for console output:
Bit Meaning
0 Key click on/off
1 Key repeat on/off
2 Tone after CTRL G on/off
3 "kbshift” is returned in bits 24-31 for the
BIOS function "conin”
$48E 4L themd 0
Memory descriptor, filled out by the BIOS function getrapb.
$49E 2W rod 0
Space for additional memory descriptors.
$4A2 L savptr $90C
Pointer to a save area for the processor registers after a BIOS call.
$4A6 W _nflops 2
Number of connected floppy disk drives (0 or 2).
$4A8 L con_state $FC41BC / $A04A
Vector for screen output; set by ESC functions to the appropriate
routine, for example.
$4 AC W save_row 0
Temporary storage for positioning the cursor with ESC Y.
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$4AE L sav_context 0
Pointer to a temporary areas for exception handling.
$4B2 2L Jbufl $ 60A4 , $60CC
Pointer to two buffer list headers of GEMDOS. The first header is
responsible for data sectors, the second for the FAT (file allocation
table) and the directory. Each buffer control block (BCB) is
constructed as follows:
long
BCB
$4F8A,
pointer to next BCB
int
drive
-1,
drive number or -1
int
type
2
buffer type
int
rec
$41C
record number in this buffer
int
dirty
0
dirty flag (buffer changed)
long
DMD
$2854
pointer to drive media descriptor
long
buffer
$4292
pointer to the buffer itself
$4BA L _hz_200 $71280
Counter for 200 Hz system clock
$4BE 4B the_env 0
Default environment string, four zero bytes.
$4C2 L _drvbita 3
32-bit vector for connected drives. Bit 0 stands for drive A, bit 1 for
drive B, and so on.
$4C6 L _dskbufp $167 A
Pointer to a 1024-byte disk buffer. The buffer is used for GSX
graphic operations and should not be used by interrupt routines.
$4CA L _autopath 0
Pointer to autoexecute path.
$4CE 8L _vbl_list $FD03C4 , 0 , 0 . . / $16252,0,0..
List of the eight standard VBL routines.
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$4EE W _dumpflg $FFFF
This flag is incremented by one when the ALT and HELP keys are
pressed simultaneously. A value of one generates a hardcopy of the
screen on the printer. A hardcopy can be interrupted by pressing ALT
HELP again.
$4F2 L _sysbase $FCOOOO / $6100
Pointer to start of the operating system.
$4F6 L _shell_j? 0
Global shell information.
$ 4FA L end_os $A100 / $3A4A0
Pointer to the end of the operating system in RAM, start of the TP A.
$ 4FE L exec_08 $FD8E98 / $1F600
Pointer to the start of the AES. Normally branched to after the
initialization of the BIOS.
$502 L dump_vec $FC0C2C / $6ABA
This vector is jumped to when a hardcopy is being printed (XBIOS
function 20).
$506 L prt_stat $FC1F34 / $7D2E
Printer status vector for hardcopy.
$50A L prt_vec $FC1EA0 / $7D2E
Printer output vector for hardcopy.
$50E L aux_stat $FC1F6E / $7DFC
Vector for getting serial output status during hardcopy.
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$512 L aux__vec $FC1F8 6 / $7E14
Vector for serial output of the hardcopy function.
$51A L memval3 $5555AAAA
Contains the variable of the "magic number" memval. Keeps the
memory configuration constant after a reset (together with memvalid
and memvalid2).
$51E 8L bconstat_vec $FC0670, $FC2138, $FC2226,
$FC2044, $FC0670, $FC0670,
$FC0670, $FC0670
Eight pointer to routines for getting input status (BIOS function 1,
bconstat). The first value applies to device number 0, the next for
device 1, etc., up to device 7. The address $FC0670 points direct to
an rts command.
$53E 8L bconin_vec $FC2104, $FC2150, $FC223C,
$FC2060,$FC0670,$FC0670,
$FC0670, $FC0670
The vector table has an equivalent function to the above. There,
however, the addresses for BIOS function 2 (bconin) are kept.
$55E 8L bcostat_vec $FC2124, $FC219A, $FC226C,
$FC21DC, $FC2004, $FC0670,
$FC0670, $FC0670
These addresses contain the output status for device numbers 0 to 7.
They are jumped to from BIOS function 8, bcostat.
$57E 8L bconout_vec $FC20 90 , $FC21B4 , $FC434C,
$FC2016, $FC21EE, $FC4340,
$FC0670, $FC0670
These addresses are the ones for character output. These correspond
to the BIOS function 3, bconout.
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3.8 The 68000 Instruction Set
If you are already familiar with the machine language of some 8-bit
processor, forget everything you know. If you do, it will make it easier to
understand the following material!
The 68000 processor is fundamentally different in construction and
architecture from previous processors (including the 8086!). The essential
difference does not lie in the fact that the standard processing width is 16
and not 8 bits (which is sometimes a drawback and can lead to
programming errors), but in the fact that, with certain exceptions, the
internal registers are not assigned to a specific purpose, but can be viewed
as general-purpose registers, with which almost anything is possible.
In earlier processors, the accumulator was always the destination for
arithmetic operations, but it is completely absent in the 68000. There are
eight data registers (D0-D7) with a width of 32 bits, and as a general rule, at
least one of these is involved in an operation. There are also eight address
registers (A0-A7), each with 32 bits, which are usually used for generating
complex addresses. Register A7 has a set assignment— it serves as the stack
pointer. It is also present twice, once as the user stack pointer (USP) and
once as the supervisor stack pointer (SSP). The distinction is made because
there are also two operating modes, namely the user mode and the
supervisor mode.
These two are not only different in that they use different stack pointers, but
in that certain instructions are not legal in the user mode. These are the
so-called privileged instructions (see also instruction description), with
whose help an unwary programmer can easily "crash” the system rather
spectacularly. This is why these instructions create an exception in the user
mode. An exception, by the way, is the only way to get from the user mode
to the supervisor mode.
In addition there is the status register, the upper half of which is designated
as the system byte because it contains such things as the interrupt mask,
things which do not concern the "normal" user, making access to this byte
also one of the privileged instructions. The lower byte, the user byte,
contains the flags which are set or cleared based on the result of operations,
such as the carry flag, zero flag, etc. As a general rule, the programmer
works with these flags indirectly, such as when the execution of a branch is
made conditional on the state of a flag.
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Two things should be mentioned yet: Multi-byte values (addresses or
operands) are not stored in memory as they are with 8-bit processors, in the
order low byte/high byte, but the other way around. Four-byte expressions
(long word) are stored in memory (and the registers of course) with the
highest-order byte first.
The second is that unsupported opcodes do not lead to a crash, but cause a
special exception, whose standard handling must naturally be performed by
the operating system.
3.8.1 Addressing modes
This is probably the most interesting theme of the 68000 because the
enormous capability first takes effect through the many various addressing
modes.
The effective address (the address which, sometimes composed of several
components, finally determines the operand) is fundamentally 32 bits wide,
even if one or more the components specified in the instruction is shorter.
These are always sign-extended to the full 32-bit width.
The charm of the addressing lies in the fact that almost all instructions
(naturally with exceptions), both the source and destination operands, can
be specified with one of the addressing modes. This means that even
memory operations do not necessarily have to use one of the registers,
memory-to-memory operations are possible.
In the assembler syntax, the source operand is given first, followed by the
destination operand (behind the comma).
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Register Direct
The operand is located in a register. There are two kinds of register direct
addressing: data register direct and address register direct.
In the first case, the operand may be bit, byte, word, or long word-oriented;
in the second case a word or long word is required, in case the address
register is the destination of the operation.
Example: ADD . B D0,D1 or ADDA. W D0,A2
Absolute Data Addressing
The operand is located in the address space of memory. This can also be a
peripheral component, naturally (see MOVEP). The address is specified in
absolute form.
This can have a width of a long word, whereby the entire address space can
be accessed, or it can be only one word wide. In this case is sign-extended
(the sign being the highest-order bit) to 32 bits. For example, the word
$7FFF becomes the long word $00007FFF, while $FFFF becomes
$FFFFFFFF. Only the lower 32K and the upper 32K of the address space
can be accessed with the short form. This addressing mode is often used in
the operating system of the ST because important system variables are
stored low in memory and all peripheral components are decoded at the top.
Example: MOVE.L $7FFF, $01234567
Instructions in which both operands are addressed with a long word are the
longest instructions in the set, consisting of 10 bytes.
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Program Counter Relative Addressing
This addressing mode allows even constants to be addressed in a completely
relocatable program, since the base of the address calculation is the current
state of the program counter.
The are two variations. In the first, a 16-bit signed offset is added to the
program counter, and in the second, the contents of a register
(sign-extended if only one word is specified) are also added in, though here
the offset may be only 8 bits long.
Example: MOVE.B $1234 (PC) , $12 (PC, DO .W)
Register Indirect Addressing
There are several variations of this, and they will be discussed individually.
Register Indirect
Here the operand address is located in an address register.
Example: CLR.L (AO)
Postincrement Register Indirect
The operand is addressed as above, but the contents of the address register
are incremented by the operand length, by 1 for xxx.B or 4 for xxx.L.
Example: MOVE.B #0, (A0 + ) , (Al)+ or CMP.L #23, (Al) +
Predecrement Register Indirect
Here the address register is decrement by the length of the operand before
the addressing.
Example: CMPI.W $0123, -(A3)
Register Indirect with Offset
A 16 bit offset will be added to the contents of the address register.
Example: EOR.L DO, $1234 (A4)
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Indexed Register Indirect with Offset
As above, but the contents of another register (address or data) are also
added in, taking the sign into account. The offset may have a width of 8 bits
here, however.
Example: MOVE . w $12 (A5, A6 . L) , D1
Immediate Addressing
Here the operand is contained as such in the instruction itself. Naturally, an
operand specified in this manner can serve only as a source. The immediate
operands can, as a general rule, be any of the allowed widths.
Example: ADDI.W #$1234, D5
In the variant QUICK, the constant may be only 3 bits long, therefore
having a value from 0-7. An exception is the MOVE command, where the
constant may have 8 bits, but in which only a data register is allowed as the
destination.
Example: ADDQ.L #1,A0 or MOVEQ #123, D1
Implied Register
This addressing mode is mentioned only for the sake of completeness and in
it, an operand address is already determined by the instruction itself. The
operands are either in the program counter, in the status register, or the
system stack pointer.
Example: MOVE SR,D6
Regarding the offsets, it should be noted that they are signed numbers in
two's complement. Their highest-order bit forms the sign. With an 8-bit
value, an offset of +127/- 128 is possible, and about ±32K with 16 bits.
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3.8.2 The instructions
In the following instruction description, the individual bit patterns are not
listed since this would lead us too far in this connection. Additional
information can be gathered from books like the M68000 161 32 -Bit
Microprocessor Programmer's Reference Manual (Motorola).
The instructions are also explained only in their base form and variations are
mentioned only in name. We will briefly explain what the individual
variations can look like here.
The variations are indicated by letter after the operand. This can be one of
the following:
A indicates that the destination of the operation is an address register.
Word operations are sign-extended to 32 bits.
I indicates an immediate operand as the source of the operation. I
operands may assume all widths as a general width.
Q means quick and represents a special form of immediate addressing.
Such an operand is usually three bits wide, corresponding to a value
range of 0 to 7. This limited range has the advantage that the operand
will fit into the opcode. Since there is no special command for
incrementing a register, something like ADDQ.L #1,A0 works well in
its place. An exception is MOVEQ. Here the operand may have a value
of 0-255.
X indicates arithmetic operations which use the X flag. This flag has a
special significance. It is set equal to the carry flag for all arithmetic
operations. The carry flag, however, is also affected by transfer
operations while the X flag is not so that it remains available for further
calculations. This is especially useful for computations with higher
precision than the standard 32 bits, where temporary results must first
be saved, and where the carry flag can be changed as a result.
All instructions have a suffix after the opcode of the form .B, .W, or .L.
This suffix indicates the processing width of the operation. Although a data
register, for example, has a width of 32 bits = 4 bytes = 1 long word, the
instruction CLR.B DO clears only the lowest-order byte of the register. For
registers, .W specifies the lower word. The higher-order word is not
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explicitly addressable. If the operand is in memory, it is important to know
that .W and .L operands must begin on an even address. The same applies
for the opcode as such, which also always comprises one word.
If the destination of an operation is an address register, only operands of
type .W and .L are allowed, whereby the first is sign-extended to a long
word.
Some listings contain instructions of the form MOVE.L #27, DO. The
programmer then assumes that the assembler will produce #$0000001B
from #27.
Now to the individual instructions:
ABCD Add Decimal with Extend
There is one data format which we have not yet discussed: the BCD
format. This means nothing more than "Binary-Coded Decimal" and it
uses digits in the range 0-9. Since this information requires only 4 bits,
a byte can store a two-digit decimal number. The instruction ABCD can
then add two such numbers. The processing width is always 8 bits.
ADD Add Binary
This instruction simply adds two operands.
Variations are ADDA, ADDQ, ADDI, and ADDX.
AND Logical AND
Two operand are logically combined with each other according the
AND function.
Variation: ANDI
ASL Arithmetic Shift Left
The operand is shifted to the left byte by the number of positions given,
whereby the highest-order bit is copied into the C and X flags. A 0 is
shifted in at the right. If a data register is shifted, the processing width
can be any. The number of places to be shifted is either specified as an I
operand (3 bits) or is placed in an additional register. If a memory
location is shifted, the processing width is always one word. A counter
is then not given; it is always =1.
ASR Arithmetic Shift Right
The operand is shifted to the right, whereby the lowest bit is copied to
C and X. The sign bit is shifted over from the left. See ASL for
information about processing width and counter.
264
1
Abacus Software
Atari ST Internals
Bcc Branch Conditionally
The branch destination is always a relative address which is either one
byte or one word long (signed!). Correspondingly, the branch can
jump over a range of +127/- 128 bytes or +32K-1/-32K. The point of
reference is the address of the following instruction.
Whether or not this instruction is actually executed depends on the
required condition, which is verified by means of the flags. Here are the
variations and their conditions. A minus sign before a flag indicates that
it must be cleared to satisfy the condition. Logical operations are
indicated with for AND and for OR.
BRA Branch Always
BCC Branch Carry Clear
BCS Branch Carry Set
BEQ Branch Equal
BGE Branch Greater or Equal
BGT Branch Greater Than
BHI Branch Higher
BLE Branch Less or Equal
BLS Branch Lower or Same
BLT Branch Less Than
BMI Branch Minus
BNE Branch Not Equal
BPL Branch Plus
BVC Branch Overflow Clear
BVS Branch Overflow Set
BCHG Bit Test and Change
The specified bit of the operand will be inverted. The original state can
be determined from the Z flag. The operand is located either in memory
(width=.B) or in a data register (width=.L). The bit number is given
either as an I operand or is located in a data register.
BCLR Bit Test and Clear
The specified bit is cleared. Everything else is handled as per BCHG.
BSET Bit Test and Set
The specified bit is set. Boundary conditions are per BCHG.
BSR Branch to Subroutine
This is an unconditional branch to a subroutine. Branch distances as for
Bcc.
no condition
-C
C
z
N*V/-N*-V
N*V*-Z/-N*-V*-Z
-c*-z
Z/N*-V/-N*V
C/Z
N*-V/-N*V
N
-Z
-N
-V
V
265
Abacus Software
Atari ST Internals
BTST Bit Test
The bit is only tested as to its condition. Everything else as per BCHG.
CHK Check Register Against Boundaries
A data register is checked to see if its contents are less than zero or
greater than the operand. Should this be the case, the processor
executes an exception. The program is continued at the address in
memory location $18 (vector 6). Otherwise no action is taken. The
processing width is only word.
CLR Clear Operand
The specified operand is cleared (set to zero).
CMP Compare
The first operand is subtracted from the second without changing either
of the two operands. Only the flags are set, according to the result.
Variations: CMP A and CMPl
Both operands are addresses with the addressing mode (Ax)+ with the
variant CMPM.
DBcc Test Condition, Decrement and Branch
A data register (word) is decremented and the flags are checked for the
specified condition. A branch is performed if the condition is not
fulfilled and the register is not -1. Branch conditions and ranges as per
Bcc.
DIVS Divide Signed
The second operand is divided by the first operand, taking the sign into
account. Afterwards the second operand contains the integer quotient in
the lower word and the remainder in the upper word, which has the
same sign as the quotient. The data width of the first operand is set at
.W and at .L for the second.
DIVU Divide Unsigned
Operation as above, but the sign is ignored.
EOR Exclusive OR
The two operands are logically combined according to the rules of
EXOR.
Variations: EORI
EXG Exchange Registers
The two registers specified are exchanged with each other.
266
Abacus Software
Atari ST Internals
EX^e%erandis filled to the given processing width with its bit 7 (in the
case of .B) or bit 15 (.W).
JM Unconditional jump to the specified address. The difference between
this and BRA is that here the address is not relative but absolute, that is,
the actual jump destination.
JSR Jump to Subroutine
Jump to a subroutine. The difference from BSR is as above.
LEA Load Effective Address .
This often-misunderstood instruction loads an address register not with
the contents of the specified operand address as is normal for the other
instructions, but with the address as such\
LINK Link Stack
This instruction first places the given address register on the stack. The
contents of the stack pointer (A7) are then placed m this register and
offset specified is added to the stack pointer.
With this practical instruction, data areas can be reserved for a
subroutine, without having to make room in the program itself which
would also be impossible in programs which run in ROM. lhe
C-compiler makes extensive use of this capability for local variables.
LSL Logical Shift Left
Function and limitations as per ASL.
LSRFmftton andlimitations as per ASR, except here the sign is not shifted
in on the left, but a 0.
MOVE , , U rl
The first operand is transferred to the second.
Variations: MOVEA, MOVEQ
MO VEM Move Mulitple Registers . , , .
Here an operand can consist of a list of registers. This can be used to
place all of the registers on the stack, for instance.
Example: MOVEM.L A0-A6/D0-D7,-(A7)
267
Abacus Software
Atari ST Internals
MOVEP Move Peripheral Data
This specialty is made expressly for the operation of peripheral
components. As a general rule, these work only with an 8-bit data bus,
and are then connected only to the upper or lower 8 bits of the 68000's
data bus. If a word or long word is to be transferred, the bytes must be
passed over either the upper or lower byte of the data bus, depending
on whether the address is even or odd. The address is then always
incremented by two so that the transfer always continues on the same
half of the data bus on which it was begun. Corresponding to the
purpose of this instruction, one operand is always a data register, and
the other is always of type register indirect with offset.
MULS Multiply Signed
Signed multiplication of two operands.
MULU Multiply Unsigned
Multiplication of two operands, ignoring the sign.
NBCD Negate Decimal with Extend
A BCD operand is subjected to the operation O-operand X.
NEG Negate Binary
The operand is subjected to the treatment O-operand.
Variations: NEGX
NOP No Operation
As the name says, this instruction doesn't do anything.
NOT One's Complement
The operand is inverted.
OR Logical OR
The two operands are combined according to the rule for logical OR.
PEA Push Effective Address
The address itself, not its contents, is placed on the stack.
RESET Reset External Devices
The reset line on the 68000 is bidirectional. Not only can the processor
be externally reset, but it can also use this instruction to reset all of the
peripheral devices connected to the reset line.
This is a privileged instruction!
268
Abacus Software
Atari ST Internals
ROL Rotate Left . tU ,
The operand is shifted to the left, whereby the bit shifted out on the left
will be shifted back in on the right and the carry flag is affected.
Processing widths and shift counter as per ASL.
ROR Rotate Right
As above, but shift from left to right.
ROXL Rotate Left with Extend
As ROL, but the shifted bit is first placed in the X flag, the previous
value of which is shifted in on the right.
ROXR Rotate Right with Extend
As above, but reversed shift direction.
RTE Return from Exception .
Return from an exception routine to the location at which the exception
occurred.
RTS Return from Subroutine
Return from a subroutine to the location at which it was called.
RTR Return and Restore . _ ,
As above, but the CC register (the one with the flags) is first fetched
from the stack (on which it must have first been placed, because
otherwise execution will not return to the proper address.
SB CD Subtract Decimal with Extend
The first operand is subtracted from the second. Reter to ABCU tor
information on the data format.
See Set Conditionally . . _ ...... ,
The operand (only .B) is set to $FF if the condition is fulfilled.
Otherwise it is cleared. Refer to Bcc for the possible condition codes.
STOP
The processor is stopped and can only
external interrupt.
This is a privileged instruction!
be called back to life through an
SUB Subtract Binary
The first operand is subtracted from the second.
269
Abacus Software
Atari ST Internals
SWAP Swap Register Halves
The two halves of a data register are exchanged with each other.
TAS Test and Set Operand
The operand (only .B) is checked for sign and 0 (affecting the C and N
flags). Bit 7 is then set to 1.
TRAP
The applications programmer uses this instruction when he wants to call
functions of the operating systems. This instruction generates an
exception, which consists of continuing the program at the address
determined by the given vector number. See the chapter on the BIOS
and XBIOS for the use of this instruction.
TRAPV Trap on Overflow
If the V flag is set, an exception is generated by this instruction,
resulting in program execution continuing at the address in vector 7
TST Test
Action like TAS, but the operand is not changed.
UNLK Unlink
This instruction is the counterpart of LINK. The stack pointer (A7) is
loaded with the given address register and this is supplied with the last
stack entry. In this manner the area reserved with LINK is released.
Addendum to the condition codes: The conditions listed under Bcc are not
complete, because the additional conditions do not make sense at that point.
But the instructions DBcc and See have the additional variations T (DBT,
ST) and F (DBF, SF). T stands for true and means that the condition is
f^ys fulfilled. F stands for false and is the opposite: the condition is never
fulfilled.
DBF can also use the syntax DBRA.
270
Abacus Software
Atari ST Internals
3.9 The BIOS Listing
The situation concerning ST software has changed radically since the Spring
of 1985. Nowadays you can find a wealth of programs which are fully
supported by GEM, and as a consequence are easy to operate. In addition,
many dealers have gone over exclusively to the ST.
One thing is certain: If available software and hardware under development
are any indicators, the Atari ST has caught on as an incredibly popular
computer.
The following is the commented BIOS listing of the Atari ST. It is patterned
after the ROM version of February 1986. The listing includes system
initialization, the complete BIOS and XBIOS, as well as the VT52 screen
driver. We don't expect any changes to this listing in the near future. Any
alterations to the ST that affect this listing will be reflected in later editions
of this book (we plan on keeping abreast of any changes, naturally).
The variables in the ROM version lie in the same range (up to $6100) as the
diskette version of TOS from February 1986.
If you want to use system routines from TOS in your own programs you
should only use the call through the corresponding TRAP. Otherwise, your
program won't run with any altered versions of TOS. This applies at the
same time to the use of variables which are not contained in the list of
system variables.
Otherwise, you can call the BIOS routines as excellent illustrations in 68000
assembly language. If your own routines are to be complex and transparent,
you can convert most of them to C compiled code. Then you can recognize
most of these routines since they start with link #n, A6. A 6 as a base
register will communicate with given parameters if there is a positive offset;
a negative offset will communicate with the local variables of this routine.
272
FC0000
601E
bra
$FC0020
FC0002
0100
dc .b
1,0
FC0004
00FC002 0
dc . 1
$FC0020
FC0008
OOFCOOOO
dc.l
$FCOOOO
FC000C
00006100
dc . 1
$6100
FC0010
00FC0020
dc . 1
$FC0020
FC0014
00FEFFF4
dc . 1
$FEFFF4
FC0018
02061986
dc . 1
$02061986
FC001C
0003
dc . w
3
FC001E
0C4 6
dc . w
$0C4 6
FC0020
46FC2700
move . w
#$2700, SR
FC0024
4E70
reset
FC0026
0CB9FA52235F00FA0000
cmp. 1
#$FA52235F, $FA0000
FC0030
660A
bne
$FC003C
FC0032
4DFA0008
lea
$FC003C (PC) ,A6
FC0036
4EF900FA0004
jmp
$FA0004
FC003C
4DFA0006
lea
$FC004 4 (PC) ,A6
FC0040
60000596
bra
$FC05D8
FC0044
660A
bne
$FC0050
FC0046
13F900000424FFFF8001
move . b
$424, $FFFF8001
FC0050
9BCD
sub. 1
A5,A5
FC0052
0CAD314 1592 6042 6
cmp . 1
#$31415926, $426(A5)
FC005A
6618
bne
$FC007 4
FC005C
202D042A
move . 1
$42A(A5) , DO
FC0060
4 A2D042A
tst .b
$42A(A5)
FC0064
660E
bne
$FC0074
FC0066
08000000
btst
o
Q
o
=*=
FC006A
6608
bne
$FC007 4
FC006C
2040
move . 1
DO, A0
FC006E
4DFAFFE0
lea
$FC0050 (PC) , A6
ATARI ST ROM-BIOS
to start of program
Version 1
Reset address
Start of the operating system
Start of free RAM
Default shell (reset)
Address for GEM magic
Creation date 2/6/1986
Flag for PAL version
Date in DOS format
Supervisor mode, IPL 7
Reset peripherals
Diagnostic cartridge inserted ?
no
Load return address
Jump to cartridge
Load return address
Memory configuration valid?
no
Get memctrl
Clear A5
resvalid, resvector valid ?
No
Load resvector
Test bits 24-31
Set, vector invalid
Address odd?
Yes, invalid
Load address
Load return address
K>
■-a
u>
FC0072 4 EDO
FC0074 4 1F9FFFF8800
FC007A 10BC0007
FC007E 117C00CCI0002
FC0084 lOBCOOOE
FC0088 117C00070002
FC008E 083A0000FF8B
FC0094 6710
FC0096 4DFA0006
FC009A 60000C4 8
FC009E 13FC0002FFFF820A
FC00A6 43F9FFFF8240
FCOOAC 303C000F
FCOOBO 41FA054C
FC00B4 32D8
FC00B6 51C8FFFC
FCOOBA 13FC0001FFFF8201
FC00C2 13FC0000FFFF8203
FCOOCA 9BCD
FCOOCC 1C2D0424
FCOODO 2A2D042E
FC00D4 4DFA0006
FC00D8 600004FE
FCOODC 670000E4
FCOOEO 4246
FC00E2 13FC000AFFFF8001
FCOOEA 307C0008
FCOOEE 43F900200008
FC00F4 4240
FC00F6 30C0
FC00F8 32C0
FCOOFA D07CFA54
jmp
(A0)
lea
$FFFF8800 , A0
move . b
#7, (A0)
move . b
#$C0,2 (A0)
move . b
#$E, (A0)
move . b
#7,2 (A0)
btst
#0, $FC001B (PC)
beq
$FC00A6
lea
$FC009E (PC) , A6
bra
$FC0CE4
move . b
#2, $FFFF820A
lea
$FFFF8240 , A1
move . w
#$F , DO
lea
$FC05FE (PC) , A0
move . w
(A0) +, (Al) +
dbra
DO, $FC00B4 .
move . b
#1 , $FFFF8201
move .b
#0, $FFFF8203
sub.l
A5,A5
move . b
$424 ( A5) ,D6
move . 1
$42E(A5) ,D5
lea
$FC00DC (PC) ,A6
bra
$FC05D8
beq
$FC01C2
clr .w
D6
move . b
#$A, $FFFF8001
move .w
#8, A0
lea
$200008, Al
clr .w
DO
move . w
DO, (A0) +
move . w
DO, (Al) +
add.w
#$FA54 , DO
Jump via vector
Address of the PSG
Port A and B
To output
Select port A
Deselect floppies
Pal version ? (must be $FC001D)
No
Load return address
Sync mode to 50 Hz Pal
Address of the color palette
16 colors
Address of the color table
Copy color in palette
Next color
dbaseh
dbasel, video address to $10000
Clear A5
memctrl
phystop
Load return address
Memory configuration valid?
Yes
Start value for memory controller
Memory controller to 2 * 2 MB
Start address for memory test
A1 points to second bank
Clear bit pattern to be written
Write pattern
Write to other address range
Next bit pattern
Abacus Software Atari ST Internals
274
FCOOFE
B1FC00000200
cmp. 1
#$200, A0
End address reached?
FC0104
66F0
bne
$FC00F6
No
FC0106
223C00200000
move . 1
#$200000, D1
D1 equals second bacnk
FC010C
E44E
lsr . w
#2 , D6
FC010E
307C0208
move . w
#$208, A0
Is bit pattern at $208 ?
FC0112
4BFAOOO 6
lea
$FC011A(PC) , A5
Load return address
FC0116
600004AA
bra
$FC05C2
Memory test
FC011A
6720
beq
$FC013C
OK, 128 K
FC011C
307C0408
move . w
#$408, A0
At $408 ?
FC0120
4BFAOOO 6
lea
$FC0128 (PC) , A5
Load return address
FC0124
6000049C
bra
$FC05C2
Memory test
FC0128
6710
beq
$FC013A
OK, 512 K
FC012A
307C0008
move . w
#$8, A0
At $8
FC012E
4BFA0006
lea
$FC0136 (PC) ,A5
Load return address
FC0132
6000048E
bra
$FC05C2
Memory test
FC0136
6604
bne
$FC013C
Nothing in this bank
FC0138
5846
addq . w
#4 , D6
FC013A
5846
addq . w
#4 , D6
Configuration byte to 2 MB
FC013C
92BC00200000
sub. 1
#$200000, D1
Next bank
FC0142
67C8
beq
$FC010C
Test for first bank
FC0144
13C6FFFF8001
move . b
D6, $FFFF8001
Program memory controller
FC014A
287900000008
move . 1
$8, A4
Save Bus Error vector
FC0150
41FA0036
lea
$FC0188 (PC) , A0
Address of new Bus-Error routine
FC0154
23C800000008
move . 1
A0, $8
Set
FC015A
363CFB55
move . w
#$FB55,D3
Start bit pattern
FC015E
2E3C00020000
move . 1
#$20000, D7
Start address is 128 K
FC0164
2047
move . 1
D7, A0
Save current
FC0166
2248
move . 1
A0, A1
address
FC0168
3400
move . w
DO, D2
FC016A
722A
moveq. 1
#42, D1
43 words
FC016C
3302
move . w
D2 , - (Al)
Write bit pattern in RAM
FC016E
D443
add . w
D3, D2
Change pattern
i
Abacus Software Atari ST Internals
275
FC0170
51C9FFFA
dbra
Dl, $FC016C
FC0174
2248
move . 1
A0, A1
FC0176
722A
moveq . 1
#42, Dl
FC0178
BO 61
cmp . w
-<A1) , DO
FC017A
660C
bne
$FC0188
FC017C
4251
clr .w
(Al)
FC017E
D043
add.w
D3, DO
FC0180
51C9FFF6
dbra
Dl, SFC0178
FC0184
D1C7
add. 1
D7, A0
FC0186
60DE
bra
$FC0166
FC0188
91C7
sub. 1
D7, A0
FC018A
2A08
move . 1
A0, D5
FC018C
23CC00000008
move . 1
A4 , $8
FC0192
2045
move . 1
D5, A0
FC0194
283C00000400
move . 1
#$400, D4
FC019A
4CFAOOOF0450
movem . 1
$FC05EC (PC) , D0-D3
FC01A0
4 8EOFOOO
movem . 1
D0-D3, - (A0)
FC01A4
B1C4
cmp. 1
D4 , A0
FC01A6
66F8
bne
$FC01AO
FC01A8
9BCD
sub. 1
A5, A5
FC01AA
1B460424
move . b
D6, $424 (A5)
FC01AE
2B45042E
move . 1
D5, $42E(A5)
FC01B2
2B7C752019F 30420
move . 1
#$752019F3, $420 (A5)
FC01BA
2B7C237 698AA043A
move . 1
#$237 6 98AA, $43A (A5)
FC01C2
9BCD
sub. 1
A5 , A5
FC01C4
307C093A
move . w
#$ 93A, A0
FC01C8
227C00010000
move . 1
#$10000, Al
FC01CE
7000
moveq. 1
#0, DO
FC01D0
30C0
move . w
DO, (A0) +
FC01D2
B3C8
cmp. 1
A0, Al
FC01D4
66FA
bne
$FC01D0
Write next bit pattern
Repeat address
43 words
Is bit pattern in RAM?
No, terminate test
Clear RAM
Change bit pattern
Test next word
Increment address by 128K
Continue testing
Address minus 128 K
Save
Restore old Bus-Error vector
Highest address for clear
Lower bound for clear
Clear registers D0-D3
Clear 16 bytes
Lower bound reached?
No, continue
Clear A5
memctrl
Highest RAM address as phystop
magic to memvalid
magic to memval2
Clear A5
End of the system variables
to current video address
Clear memory
End address reached?
No
Abacus Software Atari ST Internals
276
FC01D6
206D042E
move . 1
$42E (A5) , AO
phystop
FC01DA
91FC00008000
sub . 1
#$8000, A0
minus 32 K
FC01E0
2B48044E
move . 1
A0, $44E(A5)
equals v bs ad
FC01E4
13ED044FFFFF8201
move . b
$44F(A5) , $FFFF8201
dbaseh
FCOIEC
13ED0450FFFF8203
move . b
$450 ( A5) , $FFFF8203
dbasel
FC01F4
323C07FF
move . w
#$7FF,D1
32 K
FC01F8
2 OCO
move . 1
DO, (A0) +
FCOIFA
2 OCO
move . 1
DO, (A0) +
Clear screen
FCOIFC
20C0
move . 1
DO, (A0) +
FCOIFE
20C0
move . 1
DO, (A0) +
FC0200
51C9FFF6
dbra
Dl, $FC01F8
Next 16 bytes
FC0204
207AFE0E
move . 1
$FC0014 (PC) , A0
Address os magic
FC0208
0C9087654321
cmp. 1
#$87654321, (A0)
magic present ?
FC020E
6704
beq
$FC0214
Yes
FC0210
4 1FAFDF6
lea
$FC0008 (PC) , A0
Else use system addresses
FC0214
23E80004 000004 FA
move . 1
4 (A0) , $4 FA
end os
FC021C
23E80008000004FE
move . 1
8 (A0) , $4FE
exec_os
FC0224
2B7C00FC0D60046A
move . 1
#$FC0D60,$46A(A5)
hdv in it
FC022C
2B7C00FC10D204 7 6
move . 1
#$FC10D2, $476 (A5)
hdv rw
FC0234
2B7C00FC0DE604 72
move . 1
#$FC0DE6, $472 (A5)
hdv bpb
FC023C
2B7C00FC0F96047E
move . 1
#$FC0F96, $47E(A5)
hdv_mediach
FC0244
2B7COOFC137C047A
move . 1
#$FC137C,$47A(A5)
hdv boot
FC024C
2B7C00FC1F340506
move . 1
#$FC1F34,$506(A5)
prt stat
FC0254
2B7CO0FC1EA0050A
move . 1
#$FC1EA0, $50A(A5)
prt vec
FC025C
2B7C00FC1F6E050E
move . 1
#$FC1F6E,$50E(A5)
aux stat
FC0264
2B7C00FC1F86O512
move . 1
#$FC1F86,$512(A5)
aux vec
FC026C
2B7C00FC0C2C0502
move . 1
#$FC0C2C, $502 (A5)
dump vec
FC0274
2B6D044E0436
move . 1
$4 4E ( A5) , $436 (A5)
_v_bs_ad to memtop
FC027A
2B6D04FA0432
move . 1
$4FA(A5) , $432 (A5)
end_os to membot
FC0280
4FF900004DB8
lea
$4DB8, A7
Initialize system stack point'
FC0286
3B7C00080454
move . w
#8, $454 (A5)
nvbls
FC028C
50ED0444
St
$444 (A5)
fverify
Abacus Software Atari ST Internals
LLZ
FC0290 3B7C0 0030 4 4 0 move.w #3,$440(A5)
FC0296 2B7C0000167A04C6 move . 1 #$167A, $4C6 ( A5)
FC029E 3B7CFFFF04EE move.w #-l,$4EE(A5)
FC02A4 2B7COOFC000004F2 move . 1 #$FCOOOO, $4F2 (A5)
FC02AC 2B7C0000093A04A2 move . 1 #$ 93A, $4 A2 ( A5)
FC02B4 2B7COOFCO5CO046E move . 1 #$FC05C0, $46E (A5)
FC02BC 47FA0466 lea $FC0724 (PC) , A3
FC02C0 4 9FA02FE lea $FC05C0 (PC) , A4
FC02C4 0CB9FA52235F00FA0000 cmp.l #$FA52235F, 3FA0000
FC02CE 6726
FC02D0 43FA0748
FC02D4 D3FC02000000
FC02DA 4 1F900000008
FC02E0 303C003D
FC02E4 2 0C9
FC02E6 D3FC01000000
FC02EC 51C8FFF6
FC02F0 23CB00000014
FC02F6 2B7COOFCO 634 0070
FC02FE 2B7C00FC061E0068
FC0306 2B4B0088
FC030A 2B7C0OFCO7 4E00B4
FC0312 2B7C00FC07 4 800B8
FC031A 2B7C00FC9CA20028
FC0322 2B4C0400
FC0326 2B7C00FC07 440404
FC032E 2B4C0408
FC0332 4 1ED04CE
FC0336 2B480456
FC033A 303C0007
FC033E 4298
FC0340 51C8FFFC
beq $FC02F6
lea $FC0A1A(PC) , A1
add. 1 #$2000000, A1
lea $8, A0
move.w #$3D,D0
move .1 A1 , ( A0 ) +
add. 1 #$1000000, A1
dbra D0,$FC02E4
move . 1 A3, $14
move . 1 #$FC0634,112(A5)
move . 1 #$FC061E, 104 (A5)
move . 1 A3,136(A5)
move . 1 #$FC074E, 180 (A5)
move . 1 #$FC0748, 184 (A5)
move . 1 #$FC9CA2, 40 (A5)
move.l A4,$400(A5)
move . 1 #$FC07 4 4 , $4 04 ( A5 )
move.l A4,$408(A5)
lea $4CE ( A5) , A0
move.l A0,$456(A5)
move.w #7, DO
clr.l (A0) +
dbra D0,$FC033E
seek rate to 3 ms
_dskbufp
clear _dumpflg
_sysbase to ROM start
savptr for BIOS
swv vec for monitor change to rts
Address rte
Address rts
Diagnostic cartridge inserted ?
Yes
Indicate address for exception
Vector number in bits 24-31 to 2
Start with Bus Error
62 vectors
Set vector
Increment vector number
Initialize next exception vector
'Division by Zero' to rte
VBL interrupt, IPL 4
HBL interrupt, IPL 2
TRAP #2 to rte
TRAP #13 vector
TRAP #14 vector
LINE A vector
etv_timer to rts
etv_critic vector
etv_term to rts
_vbl_list
as pointer to _vblqueue
8 entries
clear
Next entry
Abacus Software Atari ST Internals
278
FC0344
61001E6E
bsr
SFC21B4
Initialize mfp
FC0348
7002
moveq . 1
#2, DO
Bit 2
FC034A
6100024A
bsr
$FC0596
cartscan
FC034E
103 9FFFF82 60
move . b
$FFFF8260, DO
Video resolution
FC0354
C03C0003
and.b
#3, DO
Isolate bits 0 and 1
FC0358
B03C0003
cmp. b
#3, DO
Invalid value?
FC035C
6602
bne
$FC0360
No
FC035E
7002
moveq . 1
#2, DO
Replace with 2 for high resolution
FC0360
13C00000044C
move . b
DO, $44C
sshif tmod
FC0366
1039FFFFFA01
move . b
$FFFFFA01, DO
mfp gpip, monomon
FC036C
6B18
bmi
$FC0386
No monochrome monitor?
FC036E
4DFAO00 6
lea
$FC037 6 (PC) ,A6
No return address
FC0372
60000970
bra
$FC0CE4
FC0376
13FC0002FFFF8260
move.b
#2 , $FFFF82 60
High resolution
FC037E
13FC00020000044C
move . b
#2, $44C
sshiftmod
FC0386
4EB900FCA7C4
jsr
$FCA7C4
Initialize screen output
FC038C
0C3900010000044C
cmp.b
#1, $44C
sshiftmod
FC0394
660A
bne
$FC03A0
Not medium resolution ?
FC0396
33F9FFFF825EFFFF8246
move . w
$FFFF825E, $FFFF8246
Copy color 15 (black) to color 3
FC03A0
2B7C00FC0020046E
move . 1
#$FC0020,$46E(A5)
swv vec to teset
FC03A8
33FC000100000452
move . w
#1, $452
vblsem
FC03B0
4240
clr .w
DO
Bit 0
FC03B2
610001E2
bsr
$FC0596
cartscan
FC03B6
4 6FC2300
move . w
#$2300, SR
IPL 3
FC03BA
7001
moveq. 1
#1 , DO
Bit 1
FC03BC
610001D8
bsr
$FC0596
cartscan
FC03C0
61004798
bsr
$FC4B5A
Initialize DOS
FC03C4
3F3 900FC001E
move . w
$FC001E, - ( A7 )
Creation date in DOS format
FC03CA
3F3C002B
move . w
#$2B, - (A7 )
Set date
FC03CE
4E4 1
trap
#1
GEMDOS
FC03D0
584F
addq.w
#4, A7
Correct stack pointer
FC03D2
610000B8
bsr
$FC048C
Boot from floppy
Abacus Software Atari ST Internals
FC03D6
610000D0
bsr
$FC04A8
FC03DA
61000944
bsr
$FC0D2 0
FC03DE
4A7 9000004 82
tst . w
$482
FC03E4
6718
beq
$FC03FE
FC03E6
61004194
bsr
$FC457C
FC03EA
61000728
bsr
$FC0B14
FC03EE
487A0099
pea
$FC04 89 (PC)
FC03F2
487A0095
pea
$FC0489 (PC)
FC03F6
487A007E
pea
$FC047 6 (PC)
FC03FA
4267
clr .w
- (A7)
FC03FC
605C
bra
$FC045A
FC03FE
61000714
bsr
$FC0B14
FC0402
4 1FA0066
lea
$FC04 6A (PC) , A0
FC0406
327C0840
move . w
#$840, A1
FC040A
OC100023
cmp.b
#35, (A0)
FC040E
6602
bne
$FC0412
FC0410
2449
move . 1
A1,A2
FC0412
12D8
move . b
(A0) +, (Al) +
FC0414
6AF4
bpl
$FC040A
FC0416
103900000446
move . b
$446, DO
FC041C
D03C004 1
add.b
#$41, DO
FC0420
1480
move . b
DO, ( A2 )
FC0422
487900000840
pea
$840
FC0428
487900FC0489
pea
$FC0489
FC042E
487A0059
pea
$FC048 9 (PC)
FC0432
3F3C0005
move . w
#5, - (A7)
FC0436
3F3C004B
move . w
#$4B, - (A7 )
FC043A
4E4 1
trap
#1
FC043C
DEFC000E
add.w
#$E, A7
FC0440
2040
move . 1
DO, A0
FC0442
217 9000004 FE0008
move . 1
$4FE, 8 (A0)
FC044A
487900000840
pea
$840
Boot from DMA bus
Execute reset-resident programs
_cmdload ?
No
Turn cursor on
autoexec, execute programs in AUTO folder
Null name
Null name
' COMMAND. PRG'
Load and start program
Load to program
autoexec, execute programs in AUTO folder
' PATH= 1
Address for environment
'#', place holder for drive?
No
Save address
Copy filenames
Next byte
_bootdev
'A'
Insert drive number
environment
Null name
.Null name
Create base page
exec
GEMDOS
Correct stack pointer
Address of the base page
exec_os, start address AES and Desktop
environment
Abacus Software Atari ST Internals
280
FC0450
2F08
move . 1
A0, - (A7)
FC0452
4 87A0035
pea
SFC0489 (PC)
FC0456
3F3C0004
move . w
#4 , - (A7)
FC045A
3F3C004B
move . w
#$4B,-(A7)
FC045E
4E4 1
trap
#1
FC0460
DEFC000E
add.w
#$E,A7
FC0464
4EF900FC0020
jmp
$FC0020
FC046A
504154483D00
dc .b
' PATH= 1 , 0
FC0470
233A5C0000FF
dc.b
'#:\',0,0,$f:
FC0476
434F4D4D414E442E
dc .b
* COMMAND. PRG
FC047E
50524700
FC0482
47454D2E505247
dc.b
'GEM.PRG'
FC0489
000000
dc.b
o
o
o
************************************************-
FC048C
7003
moveq. 1
#3, DO
FC048E
61000106
bsr
$FC0596
FC0492
20790000047A
move . 1
$4 7A, A0
FC0498
4E90
jsr
(A0)
FC049A
4A40
tst . w
DO
FC049C
6608
bne
$FC04A6
FC049E
4 1F900001 67A
lea
$167A, A0
FC04A4
4E90
jsr
(A0)
FC04A6
4E75
rts
*************************************************
FC04A8
7E00
moveq. 1
#0, D7
FC04AA
612A
bsr
$FC04D6
FC04AC
6620
bne
$FC04CE
FC04AE
2079000004C6
move . 1
$4C6, AO
FC04B4
323CO0FF
move . w
#$FF,D1
FC04B8
7000
moveq . 1
#0, DO
FC04BA
D058
add.w
(A0) + , DO
FC04BC
51C9FFFC
dbra
Dl, 5FC04BA
Address of the base page
Null name
Start program
exec
GEMDOS
Correct stack pointer
it return to reset
Boot from floppy
Bit 3
cartscan
hdv_boot
Load boot sector
Executable ?
No
Address of the disk buffer
Execute boot sector
dmaboot, load boot sector from DMA bus
Begin with device 0
dmaread, load boot sector
Error, test next device
_dskbufp
$100 words
Clear sum
Generate checksum
Next word
Abacus Software Atari ST internals
FC04CO B07C1234
FC04C4 6608
FC04C6 2079000004C6
FC04CC 4E90
FC04CE DE3C0020
FC04D2 66D6
FC04D4 4E75
*************************
FC0 4D6 4DF9FFFF8 60 6
FC04DC 4BF9FFFF8604
FC04E2 50F90000043E
FC04E8 2F39000004C6
FC04EE 13EF0003FFFF860D
FC04F6 13EF0002FFFF860B
FC04FE 13EF0001FFFF8609
FC0506 584F
FC0508 3CBC0098
FC050C 3CBC0198
FC0510 3CBC0098
FC0514 3ABC0001
FC0518 3CBC0088
FC051C 1007
FC051E 803C0008
FC0522 4840
FC0524 303C0088
FC0528 614C
FC052A 662A
FC052C 7C03
FC052E 4 1FA003 6
FC0532 2018
FC0534 6140
FC0536 661E
cmp . w
#$1234, DO
bne
$FC04CE
move . 1
$4C6, A0
jsr
(A0)
add.b
#$20, D7
bne
$FC04AA
rts
lea
$FFFF8606, A6
lea
$FFFF8 604 , A5
st
$43E
move . 1
$4C6, - (A7 )
move . b
3 ( A7 ) , $FFFF8 60D
move . b
2 ( A7 ) , $FFFF860B
move . b
1 ( A7 ) , $FFFF8609
addq . w
#4 , A7
move . w
#$98, (A6)
move .w
#$198, (A6)
move . w
#$98, (A6)
move . w
#1, (A5)
move . w
#$88, (A6)
move . b
D7 , DO
or .b
#8, DO
swap
DO
move . w
#$88, DO
bsr
$FC057 6
bne
$FC055 6
moveq . 1
#3, D6
lea
$FC0566 (PC) , A0
move . 1
(A0) +, DO
bsr
$FC057 6
bne
$FC055 6
Executable sector?
No
_dskbuf p
Execute boot sector
Next device number
All 8 devices?
dmaread, load boot sector from DMA bus
DMA control register
DMA data register
set flock
_dskbufp
Set DMA address
Correct stack pointer
Toggle R/W,
to allow READ
sector-count register to 1
Select DMA bus
Device number << 5
OR with read command
Output byte to DMA bus
timeout, terminate
Counter to 4
Pointer to command word table
Get command
Output on DMA bus
timeout, terminate
Abacus Software Atari ST Internals
282
FC0538 51CEFFF8
FC053C 2ABCOOOOOOOA
FC0542 323C0190
FC0546 6132
FC0548 660C
FC054A 3CBC008A
FC054E 3015
FC0550 C07C00FF
FC0554 6702
FC0556 7 OFF
FC0558 3CBC0080
FC055C 4A00
FC055E 51F90000043E
FC0564 4E75
★ •*•***★**★★★★*****★★******71?*
FC0566 0000008A
FC056A 0000008A
FC056E 0000008A
FC0572 0001008A
FC0576 2A80
FC0578 720A
FC057A D2B9000004BA
FC0580 08390005FFFFFA01
FC0588 670A
FC058A B2B9000004BA
FC0590 66EE
FC0592 72FF
FC0594 4E75
dbra D6, $FC0532
move . 1 #$ A, (A5)
move.w #$190, D1
bsr $FC057A
bne $FC0556
move . w #$8A, (A6)
move . w (A5) , DO
and.w #$FF, DO
beq $FC0558
moveq.l #-l , DO
move . w #$80, (A6)
tst.b DO
sf $4 3E
r***************************
dc.l $0000008A
dc.l $0000008A
dc.l $0000008A
dc.l $0001008A
move .1 DO, (A5)
moveq.l #10, D1
add. 1 $4BA,D1
btst #5, $FFFFFA01
beq $FC0594
cmp.l $4BA,D1
bne $FC0580
moveq.l #-l,Dl
rts
Next command
Send byte 6 (last byte)
Write byte
timeout, terminate
Select status register
Read status
Isolate bits 0-7
ok
Return code for error
DMA chip back to floppy operation
Set flags
Clear flock
Command words for DMA chip
wcbyte, output byte to DMA bus
Output byte
Wait 1/20 second
_hz_200
mfp gpip, command processed?
Yes
_hz_200, time run out?
No, keep waiting
Return code for error
Abacus Software Atari ST Internals
283
FC0596
4 IF 900F A0000
lea
$FA0000, A0
FC059C
0C98ABCDEF42
cmp . 1
#$ABCDEF 4 2, (A0) +
FC05A2
661A
bne
$FC05BE
FC05A4
01280004
btst
DO, 4 (A0)
FC05A8
67 0E
beq
$FC05B8
FC05AA
4 8E7FFFE
movem . 1
D0-D7/A0-A6, -(A7)
FC05AE
20680004
move . 1
4 (A0) , A0
FC05B2
4E90
jsr
(A0)
FC05B4
4CDF7FFF
movem. 1
(A7 ) +, D0-D7/A0-A6
FC05B8
4A90
tst . 1
(A0)
FC05BA
2050
move . 1
(A0) , A0
FC05BC
66E6
bne
$FC05A4
FC05BE
4E75
rts
*******************************************************.
FC05C0
4E75
rts
*******************************************************^
FC05C2
D1C1
add. 1
Dl, A0
FC05C4
4240
clr.w
DO
FC05C6
43E801F8
lea
$1F8 (A0) , A1
FC05CA
B058
cmp.w
(A0) +, DO
FC05CC
6608
bne
$FC05D6
FC05CE
D07CFA54
add. w
#$FA54 , DO
FC05D2
B3C8
cmp. 1
A0, A1
FC05D4
66F4
bne
$FC05CA
FC05D6
4ED5
jmp
(A5)
*******************************************************
FC05D8
9BCD
sub. 1
A5 , A5
FC05DA
0CAD752019F30420
cmp . 1
#$752019F3, $420 (A5)
cartscan, test cartridge
Address of the cartridge
User cartridge ?
No
Corresponding bit set?
No
Save registers
Get address of the routine
and execute
Save registers
Further use?
Get address
Yes, keep testing
rts for dummy routines
Memory test
Start address
Clear bit pattern
End address
Test for bit pattern
Not equal, error
Next bit pattern
End address reached?
No
Back to call
Memory configuration valid?
Clear A5
magic in memvalid ?
Abacus Software Atari ST Internals
284
FC05E2 6608
FC05E4 0CAD2 37 6 98AA0 4 3A
FC05EC 4ED6
bne $FC05EC
cmp.l #$2 37 698AA, $43A (A5)
jmp (A6)
******** ************** ******** ******** ******* **********
FC05EE 00000000 dc . 1 0
FC05F2 00000000 dc.l 0
FC05F6 00000000 dc.l 0
FC05FA 00000000 dc.l 0
FC05FE 0777070000700770
FC0606 0007070700770555
FC060E 0333073303730773
FC0616 0337073703770000
$777, $700, $070, $770
$007, $707, $077, $555
$333, $733, $373, $773
$337, $737, $377, $000
FC061E 3F00 move.w D0,-(A7)
FC0620 302F0002 move.w 2(A7),D0
FC0624 C07C0700 and.w #$700, DO
FC0628 6606 bne $FC0630
FC062A 006F03000002 or.w #$300,2(A7)
FC0630 301F move.w (A7)+,D0
FC0632 4E73 rte
*******************************************************
FC0 634 52B9000004 66
FC063A 537900000452
FC0640 6B0000DC
FC0644 4 8E7FFFE
FC0648 52B9000004 62
FC064E 9BCD
FC0650 1039FFFF8260
addq.l #1,$466
subq.w #1,$452
bmi $FC071E
movem.l D0-D7/A0-A6, - (A7)
addq.l #1,$462
sub.l A5,A5
move . b $FFFF8260,D0
No
magic in memval2 ?
Back to call
Zero-bytes to clear
Standard color palette
White, red, green, yellow
blue, magenta, cyan, light gray
gray. It. red. It. green, It. yellow
It. blue, It. magenta. It. cyan, black
HBL interrupt
Save DO
Save status from stack
Isolate IPL mask
Not IPL 0 ?
Else set IPL 3
DO back again
VBL interrupt
_f rclock
vblsem
VB1 routine disabled?
Save registers
_vbclock
Clear A5
Get video resolution
Abacus Software Atari ST Internals
285
FC0656
C03C0003
and . b
#3, DO
FC065A
B03C0002
cmp . b
#2, DO
FC065E
6C1 8
bge
$FC0 67 8
FC0660
08390007 FFFFF AO 1
btst
#7, $FFFFFA01
FC0668
6634
bne
$FC069E
FC066A
303C07D0
move . w
#$7D0, DO
FC066E
51C8FFFE
dbra
DO, $FC066E
FC0672
1 03C0002
move . b
#2 , DO
FC0676
6016
bra
$FC068E
FC0678
08390007FFFFFA01
btst
#7 , $FFFFFA01
FC0680
671C
beq
$FC0 69E
FC0682
102D044A
move . b
$4 4A ( A5) , DO
FC0686
B03C0002
cmp.b
#2, DO
FC068A
6D02
bit
$FC068E
FC068C
4200
clr.b
DO
FC068E
1B40044C
move . b
DO, $44C (AS)
FC0692
13C0FFFF82 60
move .b
DO, $FFFF8260
FC0698
206D046E
move . 1
$4 6E (A5) , A0
FC069C
4E90
jsr
(A0)
FC069E
6100401A
bsr
$FC4 6BA
FC06A2
9BCD
sub. 1
A5 , A5
FC06A4
4AAD045A
tst . 1
$45A(A5)
FC06A8
6718
beq
$FC06C2
FC06AA
206D045A
move . 1
$45A(A5) , A0
FC06AE
43F9FFFF8240
lea
$FFFF824 0, A1
FC06B4
303C000F
move . w
#$F , DO
FC06B8
32D8
move . w
(A0) +, (Al)+
FC06BA
51C8FFFC
dbra
D0, $FC06B8
FC06BE
42AD045A
clr.l
$45A (A5)
FC06C2
4AAD045E
tst . 1
$45E(A5)
FC06C6
67 1A
beq
$FC06E2
Isolate bits 0 and 1
High resolution ?
Yes
Monochrome monitor connected ?
No
Counter
Delay loop
High resolution
Monochrome monitor connected ?
Yes
def shiftmod
High resolution ?
No
sshiftmod
shiftmd, select resolution
swv_vec
Default is reset
Flash cursor
Clear A5
colorptr
Don't load color palette?
colorptr
Address of the color register
16 colors
copy
next color
colorptr
screenpt
Don't change video address?
Abacus Software Atari ST Internals
286
FC06C8
2B6D045E044E
move . 1
$45E(A5),$44E(A5)
screenpt to v bsad
FC06CE
202D044E
move . 1
$4 4E (A5) , DO
v bs ad
FC06D2
E088
lsr . 1
#8, DO
Bits 8-15
FC06D4
13C0FFFF8203
move . b
DO, $FFFF8203
as dbasel
FC06DA
E048
lsr .w
#8, DO
Bits 16-23
FC06DC
13C0FFFF8201
move . b
DO, $FFFF8201
as dbaseh
FC06E2
610012CC
bsr
$FC19B0
flopvbl, floppy VBL routine
FC06E6
3E3900000454
move . w
$454, D7
nvbls
FC06EC
6720
beq
$FC070E
VBL list empty?
FC06EE
5387
subq. 1
#1 , D7
dbra counter
FC06F0
207900000456
move . 1
$456, A0
vblqueue
FC06F6
2258
move . 1
(A0) +,A1
Get address of the routine
FC06F8
B3FC00000000
cmp. 1
#0, A1
Not used?
FC06FE
67 0A
beq
$FC070A
To next routine
FC0700
48E70180
movem . 1
D7/A0, - (A7)
Save registers
FC0704
4E91
jsr
(Al)
Execute routine
FC0706
4CDF0180
movem. 1
(A7 ) +, D7/A0
Restore registers
FC070A
51CFFFEA
dbra
D7,$FC06F6
Next routine
FC070E
9BCD
sub. 1
A5, A5
Clear A5
FC0710
4A6D04EE
tst . w
$4EE(A5)
dumpf lg
FC0714
6604
bne
SFC071A
Not set
FC0716
61000502
bsr
$FC0C1A
Execute hardcopy
FC071A
4CDF7FFF
movem. 1
(A7) +, D0-D7 /A0-A6
Restore registers
FC071E
527900000452
addq . w
#1, $452
vblsem
FC0724
4E7 3
rte
**********************
**********************************
wvbl, wait for VBL
FC0726
4 0E7
move . w
SR, - ( A7 )
Save status
FC0728
027CF8FF
and.w
#$F8FF, SR
IPL 0, enable interrupts
FC072C
203900000466
move . 1
$466, DO
f rclock
FC0732
B0B9000004 66
cmp. 1
$466, DO
frclock not yet incremented
FC0738
67F8
beq
$FC0732
No, wait
Abacus Software Atari ST Internals
FC073A 4 6DF
FC073C 4E75
move . w (A7) +, SR
rts
********************************************************
FC073E 2F3900000404 move . 1 $404, - (A7 )
FC07 44 7 OFF moveq.l #-l,D0
FC0746 4E75 rts
★ ★A*********************************-*********'************
FC0748 4 1FA0084 lea $FC07CE (PC) , AO
FC074C 6004 bra $FC0752
********************************************************
FC074E
4 1FA004C
lea
$FC07 9C (PC) , A0
FC0752
2279000004A2
move . 1
$4A2,A1
FC0758
301F
move . w
(A7 ) +, DO
FC075A
3300
move . w
DO, - (Al)
FC075C
231F
move . 1
(A7 ) +, - (A1 )
FC075E
48E11F1F
movem. 1
D3-D7/A3-A7 , - (Al )
FC0762
23C9000004A2
move . 1
Al, $4A2
FC0768
0800000D
btst
#13, DO
FC076C
6602
bne
$FC0770
FC076E
4E6F
move . 1
USP, A7
FC0770
301F
move . w
(A7 ) +, DO
FC0772
B058
cmp . w
(A0) +, DO
FC0774
6C10
bge
$FC07 8 6
FC0776
E548
lsl . w
#2, DO
FC0778
20300000
move . 1
0 ( A0, DO . w) , DO
FC077C
2040
move . 1
DO, A0
FC077E
6A02
bpl
$FC07 82
FC0780
2050
move . 1
(A0) , A0
FC0782
9BCD
sub. 1
A5 , A5
Restore status
Critical error handler
etv_cr itic
Default to error
Execute routine
TRAP #14
Address of the TRAP #14 routines
TRAP #13
Address of the TRAP #13 routines
Load savptr
Status register to DO
Save in save area
Return address in save area
Register in save area
Update savptr
Call from supervisor mode?
Yes
Else use USP
Get function number from stack
Compare with maximum number
Too big, ignore
As long index
Get address of the routine
To AO
Direct address
Else use indirect
Clear A5
Abacus Software Atari ST Internals
288
FC0784 4E90
FC0786 22 7 9000004A2
FC078C 4CD9F8F8
FC0790 2F1 9
FC0792 3F1 9
FC0794 23C9000004A2
FC079A 4E73
jsr (AO)
move . 1 $4A2,A1
movem.l (Al) +, D3-D7/A3-A7
move.l (Al)+,-(A7)
move . w (Al)+,-(A7)
move .1 Al, $4A2
rte
FC079C 000C
FC079E 00FC0910
FC07A2 00FC087 6
FC07A6 00FC087C
FC07AA 00FC0888
FC07AE 80000476
FC07B2 00FC093C
FC07B6 00FC0954
FC07BA 80000472
FC07BE O0FCO882
FC07C2 8000047E
FC07C6 00FC08F8
FC07C8 0OFC08FE
dc.w 12
dc.l $FC0910
dc.l $FC087 6
dc.l $FC087C
dc.l $FC0888
dc.l $4 7 6 + $80000000
dc.l $FC093C
dc.l $FC0954
dc.l $472+$80000000
dc.l $FC0882
dc.l $47E+$80000000
dc.l $FC08F8
dc.l $FC08FE
FC07CE
0028
dc.w
40
FC07D0
00FC2DDC
dc.l
$FC2DDC
FC07D4
00FC05C0
dc . 1
$FC05C0
FC07D8
00FC095C
dc . 1
$FC0 95C
FC07DC
00FC0970
dc . 1
$FC0 97 0
FC07E0
00FC0976
dc.l
$FC097 6
FC07E4
00FC0982
dc . 1
$FC0982
FC07E8
00FC09D0
dc . 1
$FC09D0
Execute routine
Get savptr
Restore registers
Return address on stack
Status on stack
Update savptr
Addresses of the TRAP #13 routines
Number of routines
0, getmpb
1, bconstat
2, bconin
3, bconout
4, (indirect) rwabs
5, setexec
6, tickcal
7, (indirect) getbpb
8, bcostat
9, (indirekct) mediach
10, drvmap
11, shift
Addresses of the TRAP #14 routines
Number of routines
0, initmouse
1, rts
2, physbase
3, logbase
4, getrez
5, setscreen
6, setpalette
Abacus Software Atari ST Internals
289
FC07EC
OOFC09D8
dc . 1
$FC09D8
7,
setcolor
FC07F0
00FC159E
dc . 1
$FC159E
8,
f loprd
FC07F4
00FC167C
dc . 1
$FC1 67C
9,
f lopwr
FC07F8
00FC1734
dc . 1
$FC1734
10,
f lopfmt
FC07FC
OOFCODDC
dc . 1
$FC0DDC
11,
getdsb
FC0800
00FC1E40
dc . 1
$FC1E40
12,
midiws
FC0804
00FC240E
dc . 1
$FC240E
13,
mfpint
FC0808
00FC2732
dc . 1
$FC2732
14,
iorec
FC080C
00FC275A
dc.l
$FC275A
15,
rsconf
FC0810
00FC2EE2
dc . 1
$FC2EE2
16,
keytrans
FC0814
00FC132C
dc . 1
$FC132C
17,
rand
FC0818
OOFC1414
dc . 1
$FC1414
18,
protobt
FC081C
00FC18CE
dc . 1
$FC18CE
19,
f lopver
FC0820
OOFCOC1A
dc . 1
$FC0C1A
20,
dumpit
FC0824
OOFC46F2
dc . 1
$FC4 6F2
21,
cursconf
FC0828
00FC1D7 6
dc.l
$FC1D7 6
22,
settime
FC082C
00FC1D5C
dc . 1
$FC1D5C
23,
gettime
FC0830
00FC2F0E
dc . 1
$FC2F0E
24,
bioskeys
FC0834
OOFC1FBE
dc . 1
$FC1FBE
25,
ikbdws
FC0838
OOFC2438
dc . 1
$FC2438
26,
jdisint
FC083C
00FC2472
dc.l
$FC2472
27,
jenabint
FC0840
00FC2D4C
dc . 1
$FC2D4C
28,
giaccess
FC0844
00FC2DB6
dc . 1
$FC2DB6
29,
of fgibit
FC0848
00FC2D90
dc . 1
$FC2D90
30,
ongibit
FC084C
00FC2EA6
dc . 1
$FC2EA6
31,
xbtimer
FC0850
00FC2F2 8
dc . 1
$FC2F2 8
32,
dosound
FC0854
00FC2F3C
dc . 1
$FC2F3C
33,
setprt
FC0858
00FC2F7 0
dc . 1
$FC2F70
34,
ikbdvecs
FC085C
00FC2F4E
dc . 1
$FC2F4E
35,
kbrate
FC0860
00FC30AE
dc . 1
$FC30AE
36,
prtblk
FC0864
00FC0726
dc . 1
$FC0726
37,
wvbl
FC0868
00FC0870
dc . 1
$FC0870
38,
supexec
Abacus Software Atari ST Internals
290
FC086C 00FCO9FE
dc . 1
$FC0 9FE
FC0870 206F0004 move.l 4(A7),A0
FC0874 4ED0 jmp (AO)
********************************************************
FC0876 41FA0020 lea $FC0898 (PC) , AO
FC087A 6010 bra $FC088C
********************************************************
FC087C 4 1FA0032 lea $FC08B0 (PC) , AO
FC0880 600A bra $FC088C
********************************************************
FC0882 41FA0044 lea $FC08C8 (PC) , AO
FC0886 6004 bra $FC088C
********************************************************
FC0888 4 1FA005 6 lea $FC08E0 (PC) , AO
FC088C 302F0004 move.w 4(A7),D0
FC0890 E54 8 lsl.w #2, DO
FC0892 20700000 move.l 0 ( AO, DO . w) , AO
FC0896 4ED0 jmp (AO)
********************************************************
dc.l $FC05C0
dc.l $FC1F4 8
dc.l $FC1FD2
dc.l $FC1E54
dc.l $FC05CO
dc.l $FC05C0
FC0898 00FC05C0
FC089C 00FC1F4 8
FC08A0 00FC1FD2
FC08A4 00FC1E54
FC08A8 00FC05C0
FC08AC 00FC05C0
39, puntaes
supexec
Get address
Execute routine in the supervisor mode
bconstat, get input status
Status table
bconin, input
Input table
bcostat, get output status
Status table
bconout, output
Output table
Device number
times 4
Get address of the routine
Execute routine
Input status
rts
RS 232 status
Console status
MIDI status
rts
rts
Abacus Software Atari ST Internals
FC08B0 00FC1F14
FC08B4 OOFC1F5E
FC08B8 00FC1FE8
FC08BC 00FC1E70
FC08C0 00FC05C0
FC08C4 00FC05C0
dc.l $FC1F14
dc.l SFC1F5E
dc.l $FC1FE8
dc.l 5FC1E70
dc.l $FC05C0
dc.l $FC05C0
M3
FC08C8 00FC1F34
FC08CC OOFC1F6E
FC08D0 00FC2018
FC08D4 00FC1F92
FC08D8 00FC1E14
FC08DC OOFC05CO
dc.l $FC1F34
dc.l $FC1F6E
dc.l $FC2018
dc.l $FC1F92
dc.l $FC1E14
dc.l $FC05C0
FC08E0
00FC1EA0
dc . 1
$FC1EA0
FC08E4
00FC1F86
dc.l
$FC1F86
FC08E8
00FC41AC
dc . 1
5FC41AC
FC08EC
00FC1E2 6
dc.l
SFC1E26
FC08F0
00FC1FA4
dc . 1
SFC1FA4
FC08F4
OOFC41AO
dc.l
$FC4 1A0
********************************************************
FC08F8 202D04C2 move . 1 $4C2(A5),D0
FC08FC 4E75 rts £,nliia3;
********************************************************
FC08FE 7000 moveq.l #0,D0
FC0900 102D0E1B move.b $E1B(A5),D0
FC0904 322F0004 move.w 4(A7),D1
Input
Parallel port
RS 232 input
Console input
MIDI input
rts
rts
Output status
Centronics status
RS 232 status
Console status
MIDI status
IKBD status
rts
Output
Centronics output
RS 232 output
Console output
MIDI output
IKBD output
ASCII output
drvmap, active drives
_drvbits
Shift, keyboard status
Shift status
new shift status
Abacus Software Atari ST Internals
292
FC0908
6B04
bmi
$FC0 90E
FC090A
1B410E1B
move . b
Dl, $E1B(A5)
FC090E
4E75
rts
**************************************************.
FC0910
206F0004
move . 1
4 (A7) , AO
FC0914
43ED048E
lea
$48E(A5) ,A1
FC0918
2089
move . 1
Al, (AO)
FC091A
42A80004
clr.l
4 (AO)
FC091E
21490008
move . 1
Al, 8 (AO)
FC0922
4291
clr . 1
(Al)
FC0924
236D04320004
move . 1
$432 (A5) , 4 (Al)
FC092A
202D0436
move . 1
$436 (A5) , DO
FC092E
90AD0432
sub. 1
$432 (A5) , DO
FC0932
23400008
move . 1
DO, 8 (Al)
FC0936
42A9000C
clr.l
12 (Al)
FC093A
4E75
rts
ini ; i&3 |
**************************************************'
FC093C
302F0004
move . w
4 ( A7 ) , DO
FC0940
E548
lsl . w
#2, DO
FC0942
91C8
sub. 1
AO, A0
FC0944
41F00000
lea
0 ( A0, DO . w) , AO
FC0948
2010
move . 1
(A0) , DO
FC094A
222F0006
move . 1
6 ( A7 ) , Dl
FC094E
6B02
bmi
$FC0952
FC0950
2081
move . 1
Dl, (A0)
FC0952
4E7 5
rts
**************************************************
FC0954
4280
clr . 1
DO
FC0956
302D0442
move . w
$442 ( A5) , DO
FC095A
4E75
rts
-1, not set
Use new status
getmpb. Memory Parameter Block
Address of the mpb
themd. Memory Descriptor
mp_mfl = address of the MD
mp_mal = zero
mp rover = address of the MD
clear m_link
_membot as m_start
_memtop
minus _membot
length m_lenght
m_own = zero
setexc, set exception vector
Vector number
times 4
Clear AO
Get address of the vector
Old vector to DO
New vector
Negative, don't set
Set new vector
tickcal, timer value in milliseconds
timer ms
Abacus Software Atari ST Internals
293
FC095C 7000
FC095E 1039FFFF8201
FC0 964 El 4 8
FC0966 1039FFFF8203
FC096C E188
FC096E 4E75
moveq.l #0,D0
move . b $FFFF8201,D0
lsl.w #8, DO
move . b $FFFF8203,D0
lsl.l #8, DO
rts
********************************************************
FC0970 202D044E move . 1 $44E(A5),D0
FC0974 4E75 rts
FC0976 7000
FC0978 102D8260
FC097C C03C0003
FC0980 4E75
moveq.l #0,D0
move .b $FFFF8260 (A5) , DO
and.b #3, DO
rts
***************************’
FC0982 4 A AF 000 4
FC0986 6B06
FC0988 2B6F0004044E
FC098E 4AAF0008
FC0992 6B10
FC0994 13EF0009FFFF8201
FC099C 13EF000AFFFF8203
FC09A4 4A6F000C
FC09A8 6B2 4
FC09AA 1B6FOO0DO44C
FC09B0 6100FD7 4
FC09B4 13ED044CFFFF8260
****************************
tst.l 4 ( A7 )
bmi $FC098E
move . 1 4 ( A7 ) , $4 4E ( A5)
tst.l 8 (A7)
bmi $FC09A4
move . b 9 (A7) , $FFFF8201
move ,b 10 ( A7 ) , $FFFF8203
tst . w 12 (A7)
bmi $FC09CE
move.b 13 (A7) , $44C (A5)
bsr $FC0726
move.b $44C (A5) , $FFFF8260
physbase, physical video address
dbaseh
dbasel
Result in DO
logbase, logical video address
_v_bs_ad
getrez, get video resolution
sshiftmd
Isolate bits 0 and 1
setscreen, set screen address
Logical address
Don't set?
_v_bs_ad
physical address
Don't set?
dbaseh
dbasel
Video resolution
don't set
sshiftmod
wvbl, wait for VBL
sshiftmod to shiftmd
Abacus Software Atari ST Internals
294
FC09BC
426D0452
clr . w
$452 (A5)
vblsem, VBL disabled
FC09C0
4EB900FCA7C4
jsr
$FCA7C4
Initialize screen output
FC09C6
33FC 000100000452
move . w
#1, $452
vblsem, enable VBL again
FC09CE
4E7 5
rts
***********************************
*********************
setpalette, load new color pal<
FC09D0
2B6F0004045A
move . 1
4 ( A7 ) , $45A (A5)
colorptr, execution in VBL
FC09D6
4E7 5
rts
******:
*****************************
**********************
setcolor, set single color
FC09D8
322F0004
move . w
4 (A7 ) ,D1
Color number
FC09DC
D241
add. w
Dl, D1
times 2
FC09DE
C27C001F
and. w
#$1F,D1
Limit to valid numbers
FC09E2
41F9FFFF8240
lea
$FFFF8240 , AO
Address of color palette
FC09E8
30301000
move .w
0 (AO, Dl .w) , DO
Get color
FC09EC
C07C0777
and.w
#$777, DO
Isolate RGB bits
FC09F0
4A6F000 6
tst . w
6 ( A7 )
New color
FC09F4
6B06
bmi
$FC09FC
negative ?
FC09F6
31AF00061000
move . w
6 ( A7 ) , 0 (AO , Dl . w)
Set color
FC09FC
4E75
rts
***********************************
*********************
puntaes, clear AES and restart
FC09FE
207AF614
move . 1
$FC0014 (PC) , AO
Address os magic
FC0A02
0C9087654321
cmp. 1
#$87654321, (AO)
magic ?
FC0A08
660E
bne
$FC0A18
No, AES already disabled
FCOAOA
B1F90000042E
cmp. 1
$42E, AO
phystop, AES in ROM ?
FC0A10
6C06
bge
$FC0A18
Yes, nothing to do
FC0A12
4290
clr . 1
(AO)
clear magic
FCOA14
6000F60A
bra
$FC0020
to reset
FC0A18
4E7 5
rts
Abacus Software Atari ST Internals
295
*******************************************************
term, end program after exception
FC0A1A
6102
bsr
$FC0A1E
PC on stack
FC0A1C
4E71
nop
FC0A1E
23DF000003C4
move . 1
(hi) +, $3C4
Save PC including vector number
FC0A24
48F9FFFF00000384
movem . 1
D0-D7/A0-A7, $384
Save registers
FC0A2C
4E68
move . 1
USP, A0
USP
FC0A2E
23C8000003C8
move . 1
A0, $3C8
save
FC0A34
700F
moveq. 1
#15, DO
16 words
FC0A36
41F9000003CC
lea
$3CC, A0
Address save area
FC0A3C
224F
move . 1
A7,A1
Get stack pointer
FC0A3E
30D9
move . w
(Al) +, (A0) +
Save 16 words from stack
FC0A4O
51C8FFFC
dbra
DO, $FC0A3E
Next word
FCOA44
23FC 1234567800000380
move . 1
#$12345678, $380
magic for saved registers
FCOA4E
7200
moveq . 1
#0 , D1
FC0A50
1239000003C4
move . b
$3C4,D1
Vector number to D1
FC0A56
5341
subq.w
#1 , D1
in dbra counter
FC0A58
6116
bsr
$FC0A70
Output appropriate number of "bombs
FC0A5A
23FC0000093 AO 00004 A2
move . 1
#$93A, $4A2
Reset savptr for BIOS
FC0A64
3F3C0001
move .w
#1, - (A7)
Return code for error
FC0A68
42A7
clr.l
- (A7)
term, end program
FC0A6A
4E4 1
trap
#1
GEMDOS
FC0A6C
6000F5B2
bra
$FC0020
if return, then reset
*******************************************************
Write "bombs" to screen
FC0A7 0
1E39FFFF82 60
move . b
$FFFF8260,D7
shiftmd, get resolution
FC0A76
CE7C0003
and.w
#3, D7
Isolate significant bits
FC0A7A
DE47
add.w
D7 , D7
as word pointer
FC0A7C
4280
clr . 1
DO
FC0A7E
1039FFFF8201
move . b
$FFFF8201, DO
dbaseh
FCOA84
E148
lsl.w
#8, DO
FC0A86
1039FFFF8203
move .b
$FFFF8203, DO
dbasel
FC0A8C
E188
lsl.l
#8, DO
Abacus Software Atari ST Internals
296
FC0A8E
2040
move . 1
DO, AO
yields video address
FC0A90
D0FB702C
add. w
$FC0ABE (PC, D7 .w) , AO
plus offset for screen center
FC0A94
4 3F9O0FC0CC4
lea
$FC0CC 4 , A1
Address of the bit pattern for bombs
FC0A9A
3C3COOOF
move . w
#$F,D6
16 raster lines
FC0A9E
3401
move . w
Dl, D2
FCOAAO
2448
move . 1
AO, A2
Save pointer to start of line
FC0AA2
3A3B7022
move . w
$FC0AC6 (PC, D7 . w) , D5
Number of words (screen planes)
FC0AA6
30D1
move . w
(Al) , (AO) +
Write one raster line
FC0AA8
51CDFFFC
dbra
D5, $FC0AA6
Next screen plane
FCOAAC
51CAFFF4
dbra
D2 , $FC0AA2
Next bomb, same raster line
FCOABO
5449
addq . w
#2, Al
Next word of the bit pattern
FC0AB2
D4FB701A
add.w
$FC0ACE (PC, D7 .w) ,A2
Plus line length, next screen line
FC0AB6
204A
move . 1
A2 , AO
Start of the line
FC0AB8
51CEFFE4
dbra
D6, $FC0A9E
Next raster line
FCOABC
4E75
rts
********************************************************
Offset for screen center
FCOABE
3E80
dc.w
100*160
low resolution
FCOACO
3E80
dc .w
100*160
medium resolution
FC0AC2
3E80
dc.w
200*80
high resolution
FCOAC4
3E80
dc.w
200*80
high resolution
********************************************************
Number of screen planes - 1
FC0AC6
0003
dc.w
3
low resolution
FCOAC8
0001
dc.w
1
medium resolution
FCOACA
0000
dc.w
0
high resolution
FCOACC
0000
dc.w
0
high resolution
********************************************************
Line length in bytes
FCOACE
OOAO
dc.w
160
low resolution
FCOADO
OOAO
dc.w
160
medium resolution
FCOAD2
0050
dc.w
80
high resolution
Abacus Software Atari ST Internals
297
FC0AD4 0050
dc . w
80
high resolution
*******************************************************
FC0AD6
206F0004
move . 1
4 ( A7 ) , AO
FCOADA
22 6F0008
move . 1
8 ( A7 ) , A1
FCOADE
303C003F
moveq . 1
#63, DO
FC0AE2
12D8
move . b
(AO) +, (Al) +
FC0AE4
12D8
move . b
(AO) +, (Al) +
FC0AE6
12D8
move .b
(AO) +, (Al) +
FC0AE8
12D8
move . b
(AO) +, (Al) +
FCOAEA
12D8
move .b
(AO) +, (Al) +
FCOAEC
12D8
move . b
(AO) +, (Al) +
FCOAEE
12D8
move . b
(AO) +, (Al) +
FC0AF0
12D8
move . b
(AO) +, (Al ) +
FC0AF2
51C8FFEE
dbra
DO, $FC0AE2
FC0AF6
4E7 5
rts
***********************************
*********************
FC0AF8
2F390000046A
move . 1
$4 6A, - (A7 )
FCOAFE
4E75
rts
*******************************************************
FCOBOO
5C4155544F5C
dc . b
• \AUTO\ '
FC0B06
2A2E50524700
dc .b
' * . PRG ' , 0
FC0B0C
12345678
dc . 1
$12345678
FC0B10
9ABCDEF0
dc . 1
$9ABCDEF0
*******************************************************
FC0B14
4 1FAFFEA
lea
$FCOBOO (PC) , AO
FC0B18
43FAFFEC
lea
$FC0B06 (PC) , Al
FC0B1C
23DF0000093A
move . 1
(A7 ) +, $93A
FC0B22
9BCD
sub. 1
A5, A5
fastcopy, copy floppy sector
Source address
Destination address
(63+1) *8 = 512 bytes
Copy 8 bytes
Next 8 bytes
hdvinit, initialize drive data
hdv_init
Execute routine
autoexec, execute programs in auto folder
Address of pathname ' \AUT0\* . PRG 1
Address of filename '*.PRG'
Save return address
Clear A5
Abacus Software Atari ST Internals
298
FCOB24
2B48093E
FC0B28
2B490942
FC0B2C
202D04C2
FCOB30
323900000446
FC0B36
0300
FC0B38
6736
FC0B3A
41FAF94D
FC0B3E
2F08
FC0B40
2F08
FC0B42
2F08
FC0B44
3F3C0005
FC0B48
3F3C004B
FC0B4C
4E4 1
FC0B4E
DEFC0010
FC0B52
2040
FC0B54
217CO0FCOB78OOO8
FC0B5C
2F0B
FC0B5E
2F00
FC0B60
2F0B
FC0B62
3F3C0004
FC0B66
3F3C004B
FC0B6A
4E4 1
FC0B6C
DEFC0010
FC0B70
2F390000093A
FC0B76
4E75
move . 1
A0, $93E(A5)
move . 1
Al, $942 (A5)
move . 1
$4C2 (A5) , DO
move . w
$446, D1
btst
D1 , DO
beq
$FC0B7 0
lea
$FC0489 (PC) , A0
move . 1
A0, - (A7)
move . 1
AO, - (A7)
move . 1
A0, - (Al)
move . w
#5, - (A7)
move . w
#$4B, - (A7)
trap
#1
add.w
#$10, A7
move . 1
DO, A0
move . 1
#$FC0B78 , 8 (AO)
move . 1
A3, - (A7)
move . 1
DO, - (A7)
move . 1
A3, - (A7)
move . w
#4,-(A7)
move . w
#$4B, - (A7 )
trap
#1
add.w
#$10, A7
move . 1
$93A, - (A7 )
rts
pathname
filename
_drvbits
_bootdev
Drive active ?
No, done
Pointer to null name
Environment
Command tail
Filler
Create base page
exec
GEMDOS
Correct stack pointer
Address of the base page
Start address
Null string
Base page
Null string
Start program
exec
GEMDOS
Correct stack pointer
Repeat return address
Back to call
Call autoexec program
super
GEMDOS
Correct stack pointer
Saved stack pointer
FC0B78 42A7
FC0B7A 3F3C002 0
FC0B7E 4E4 1
FC0B80 5C4F
FC0B82 2840
clr.l - (A7 )
move.w #$20, -(A7)
trap #1
addq.w #6,A7
move . 1 D0,A4
Abacus Software Atari ST Internals
299
FC0B84 2A6F0004
FC0B88 4FED0100
FC0B8C 2F3C00000100
FC0B92 2F0D
FC0B94 4267
FC0B96 3F3C004A
FC0B9A 4E4 1
FC0B9C 5C4F
FC0B9E 4A40
FCOBAO 666A
FCOBA2 3F3C0007
FC0BA6 2F390000093E
FCOBAC 3F3C004E
FCOBBO 7E08
FC0BB2 487900000946
FC0BB8 3F3C001A
FCOBBC 4E41
FCOBBE 5C4F
FCOBCO 4E4 1
FC0BC2 DEC7
FC0BC4 4A40
FC0BC6 6644
FC0BC8 207 90000093E
FCOBCE 247900000942
FC0BD4 43F900000972
FCOBDA 12D8
FCOBDC B5C8
FCOBDE 66FA
FCOBEO 41F900000964
FC0BE6 12D8
FC0BE8 66FC
FCOBEA 4 87AF89D
move .1 4 ( A7 ) , A5
lea $100 ( A5) , A7
move . 1 #$100, -(A7)
move . 1 A5,-(A7)
clr.w — ( A7 )
move . w #$4A,-(A7)
trap #1
addq.w #6,A7
tst.w DO
bne $FC0C0C
move . w #7 , - ( A7 )
move.l $93E,-(A7)
move.w #$4E,-(A7)
moveq.l #8,D7
pea $946
move.w #$1A,-(A7)
trap #1
addq.w #6,A7
trap #1
add.w D7,A7
tst.w DO
bne $FCOCOC
move.l $93E,A0
move.l $942, A2
lea $972, A1
move . b (A0)+, (Al)+
cmp.l A0,A2
bne $FC0BDA
lea $964, A0
move.b (A0)+,(A1)+
bne $FC0BE6
pea $FC0489 (PC)
Base page address
Stack pointer to end of base page
$100 bytes for base page
Address of the program
setblock, release memory
GEMDOS
Correct stack pointer
ok ?
No, terminate
R/O, hidden and system files
Filename
Search first
Bytes for stack correction
DMA address for DOS
Setdta
GEMDOS
Correct stack pointer
GEMDOS
Correct stack pointer
Matching file found?
No
pathname
filename
autoname
copy path
End of path segment?
No, keep copying
Name from DMA buffer
Append to pathname
End of the name?
Null name
. _ „ „ Atari ST Internals
Abacus Software
300
FCOBEE 4 87AF899
pea
$FC04 89 (PC)
Null name
FC0BF2 487900000972
pea
$972
Filename
FC0BF8 4267
clr.w
- (A7)
Load and start program
FCOBFA 3F3C004B
move . w
#$4B, - (A7 )
exec
FCOBFE 4E4 1
trap
#1
GEMDOS
FCOCOO DEFC0010
add.w
#$10, A7
Correct stack
FCOC04 7E02
moveq . 1
. #2 , D7
Bytes for stack correction
FC0C06 3F3C004F
move . w
#$4F, - (A7)
Search next
FCOCOA 60A6
bra
$FC0BB2
Next program
FCOCOC 4FF900004DB8
lea
$4DB8 , A7
Stack pointer to start valui
FC0C12 2F390000093A
FC0C18 4E75
move . 1
rts
$93A, - (A7 )
Return address
***************************
********
*********************
scrdmp, screen hardcopy
FC0C1A 207900000502
move . 1
$502, A0
dump vec
FC0C20 4E90
jsr
(A0)
Execute routine
FC0C22 33FCFFFF000004EE
move . w
#-l, $4EE
clear dumpflg
FC0C2A 4E75
rts
***********************************
*********************
scrdmp
FC0C2C 9BCD
sub.l
A5, A5
Clear A5
FC0C2E 2B6D044E0992
move . 1
$44E(A5) , $992 (A5)
_v_bs ad
FC0C34 426D0996
clr.w
$996 (A5)
Offset to zero
FC0C38 4240
clr.w
DO
FC0C3A 102D044C
move .b
$4 4C (A5) , DO
sshiftmod
FC0C3E 3B4009A0
move . w
DO, $9A0 (A5)
save
FC0C42 D040
add.w
DO, DO
times 2
FC0C44 4 1FA006A
lea
$FCOCBO (PC) , AO
Table for screen resolution
FC0C48 3B7 00 0000 998
move . w
0 (AO, DO .w) , $ 998 (A5 )
Get screen width
FC0C4E 3B700006099A
move . w
6 (AO, DO . w) ,$99A(A5)
Get screen height
FC0C54 42 6D099C
clr.w
$99C(A5)
Left
FC0C58 426D099E
clr . w
$99E (A5)
and right to zero
>
r+-
to
03
H
rt>
*1
B
to
Vi
Abacus Software
FC0C5C 2B7COOFF82 4 00 9A4
FC0C64 426D09AC
FC0C68 322D0E4A
FC0C6C E649
FC0C6E C27C0001
FC0C72 3B4109A2
FC0C76 322D0E4A
FC0C7A 3001
FC0C7C E848
FC0C7E C07C0001
FC0C82 3B4009AA
FC0C86 C27C0007
FC0C8A 103B1030
FC0C8E 33C0000009A8
FC0C94 486D0992
FC0C98 33FC0001000004EE
FC0CA0 6100240C
FC0CA4 33FCFFFF000004EE
FCOCAC 584F
FCOCAE 4E75
***************************
FCOCBO 014002800280
FC0CB2 00C8Q0C80190
move . 1
#$FF82 4 0 , $ 9A4 (A5)
clr . w
$ 9AC ( A5)
move . w
$E4 A ( A5) , D1
lsr.w
#3, D1
and.w
#1 , D1
move . w
Dl, $9A2 (A5)
move . w
$E4A(A5) ,D1
move . w
o
Q
< — l
O
lsr.w
#4, DO
and.w
o
Q
«-H
4t=
move . w
DO, $9AA(A5)
and.w
#7 , Dl
move .b
$FC0CBC (PC, Dl . w) , DO
move .w
DO, $9A8
pea
$992 ( A5)
move . w
#1, $4EE
bsr
$FC30AE
move . w
#-l , $4EE
addq.w
#4 , A7
rts
dc.w 320,640,640
dc.w 200,200,400
*******************************************************
FCOCBC 00 dc.b 0
FCOCBD 02 dc.b 2
FCOCCE 01 dc-b 1
FCOCCF FF
FCOCCO 03
dc.b -1
dc.b 3
FC0CC1 FF
dc.b -1
Address of color palette
Clear mask pointer
Get printer configuration
Draft/quality mode
Isolate bit
and save
Printer configuration
Parallel/serial
Isolate bit
and save
Isolate printer type
Get assignment from table
and save for hardcopy
Address of the parameter block
_dumpflg to one
Execute hardcopy
_dumpflg copy
Correct stack pointer
Parameter table for hardcopy
Screen widths
Screen heights
Printer types { — 1 — not implemented )
ATARI B/W dot-matrix
ATARI B/W daisy wheel
ATARI color dot-matrix
(ATARI color daisy wheel)
Epson B/W dot-matrix
(Epson B/W daisy wheel)
Abacus Software Atari ST Interna,s
302
FC0CC2
FF
dc .b
-1
(Epson color dot-matrix)
FC0CC3
FF
dc .b
-1
(Epson color daisy wheel)
**i******,****4H***Ht**tim**.i*****i****tm**.*t*t
"Bomb" bit pattern
FC0CC4
0600
dc .b
%0000011000000000
FC0CC6
2900
dc .b
%0010100100000000
FC0CC8
0080
dc .b
%0000000010000000
FCOCCA
4840
dc .b
%0100100001000000
FCOCCC
UFO
dc .b
%0001000111110000
FCOCCE
01F0
dc .b
%0000000111110000
FCOCDO
07FC
dc .b
%0000011111111100
FC0CD2
OFFE
dc .b
%0000111111111110
FC0CD4
OFFE
dc .b
%oooomiinmio
FC0CD6
1FFF
dc .b
%0001111111111111
FC0CD8
1FEF
dc .b
%0001111111101111
FCOCDA
OFEE
dc.b
%0000111111101110
FCOCDC
OFDE
dc.b
%0000111111011110
FCOCDE
07FC
dc.b
%0000011111111100
FCOCEO
03F8
dc.b
%0000011111111000
FC0CE2
OOEO
dc.b
%0000000011100000
*******************************************************
FC0CE4
4 1F9FFFFFA2 1
lea
$FFFFFA2 1, AO
mfp. Timer B data
FCOCEA
43F9FFFFFA1B
lea
$FFFFFA1B, A1
mfp. Timer B control
FCOCFO
12BC0010
move ,b
#$10, (Al)
Timer B output low
FC0CF4
7801
moveq. 1
#1,D4
FC0CF6
12BC0000
move . b
#0, (Al)
Stop timer B
FCOCFA
lOBCOOFO
move . b
#$F0 , (AO)
Load timer B counter with 240
FCOCFE
13FC0008FFFFFA1B
move . b
#8, $FFFFFA1B
Timer B control, delay mode, /50
FC0D06
1010
move .b
(AO) , DO
Load counter value
FC0D08
B004
cmp . b
D4 , DO
Same last value?
FCODOA
66FA
bne
$FC0D06
No
Abacus Software Atari ST Internals
FC0D0C
1810
move . b
(AO) ,D4
FC0D0E
363C0267
move . w
#$267, D3
FC0D12
B810
cmp.b
(AO) ,D4
FC0D14
66F6
bne
$FC0D0C
FC0D16
51CBFFFA
dbra
D3 , $FC0D12
FC0D1A
12BC0010
move . b
#$10, (Al)
FC0D1E
4ED6
jmp
(A6)
LO
o
u>
FC0D20
20790000042E
move . 1
$42E, A0
FC0D26
90FC0200
sub.w
#$200, A0
FC0D2A
B1FC00000400
cmp. 1
#$400, A0
FC0D30
672C
beq
$FC0D5E
FC0D32
0C9012123456
cmp. 1
#$12123456, (AO)
FC0D38
66EC
bne
$FC0D2 6
FC0D3A
B1E80004
cmp. 1
4 (A0) , A0
FC0D3E
66E6
bne
$FC0D2 6
FC0D40
4240
clr .w
DO
FC0D42
2248
move . 1
AO, Al
FC0D44
323COOFF
move . w
#$FF,D1
FC0D48
D059
add.w
(Al) + , DO
FC0D4A
51C9FFFC
dbra
Dl, $FC0D48
FC0D4E
B07C5678
cmp. w
#$5678, DO
FC0D52
66D2
bne
$FC0D2 6
FC0D54
2F08
move . 1
A0, - ( A7 )
FC0D56
4EA80008
jsr
8 (A0)
FC0D5A
205F
move . 1
(A7) +, A0
FC0D5C
60C8
bra
$FC0D2 6
FC0D5E
4E75
rts
FC0D60 4E56FFF0 link A6,#-16
Counter value
Loop counter to 616
Counter value equal?
No, read new value
Next pass
Timer B output low
Back to call
Execute reset resident programs
phystop
minus $200
Exception vectors reached?
Yes, done
magic ?
No
Address ?
No
Clear sum
Save address
256 words
sum
Next word
magic ?
No, keep looking
Save address
Execute routine
Restore address
Keep searching
hdv_init, initialize drives
Abacus Software Atari ST Internals
304
maxacctim to 300*20 ms
clear _nflops
curflop, current drive
Start with drive A
To loop end
Address of the DSB (Device Status Block)
Drive number
as index
Clear DSB
Drive number
flopini
Correct stack pointer
Save error code
Drive number
times 2
Error code
Drive not present?
Increment _nflops
_drvbits, drive A and B
Increment drive number
2 drives tested?
No
Abacus Software Atari ST internais
FC0DDC
4E56FFFC
link
A6, #-4
FC0DE0
4280
clr . 1
DO
FC0DE2
4E5E
unlk
A6
FC0DE4
4E75
rts
FC0DE6 4E56FFF4 link A6,#-12
FCODEA 48E7070C movem.l D5-D7 /A4-A5, - ( A7 )
FCODEE OC6E00020008 cmp.w #2,8(A6)
FC0DF4 6D06 bit $FC0DFC
FC0DF6 4280 clr.l DO
FC0DF8 60000192 bra $FC0F8C
FC0DFC
302E0008
move . w
8 (A6) , DO
FC0E00
EB40
asl.w
#5, DO
FC0E02
48C0
ext . 1
DO
FC0E04
2A40
move . 1
DO , A5
FC0E06
DBFC00004DCE
add. 1
#$4DCE,A5
FC0E0C
284D
move . 1
A5,A4
FC0E0E
3EBC0001
move . w
#1, <A7)
FC0E12
4267
clr .w
- (A7)
FC0E14
4267
clr ,w
- (A7 )
FC0E16
3F3C0001
move . w
#1,-(A7)
FC0E1A
3F2E0008
move . w
8 (A6) ,-<A7)
FC0E1E
42A7
clr . 1
- (A7)
FC0E20
2F3C0000167A
move . 1
#$167A, - (A7)
FC0E26
4EB900FC159E
jsr
$FC159E
FC0E2C
DFFC00000010
add. 1
#$10, A7
FC0E32
2D40FFF4
move . 1
DO, -12 (A6)
FC0E36
4 AAEFFF 4
tst . 1
-12 (A6)
FC0E3A
6C1 6
bge
$FC0E52
getdsb
Zero
getbpb. Get BIOS parameter block
Save registers
Drive number
< 2, OK
else zero
Drive number
times 32
plus base address
save
count, read a sector
Side 0
Track 0
Sector 1
Drive number
Filler
Address of disk buffer
Read sector
Correct stack pointer
Error code
test
OK ?
Abacus Software Atari ST eternals
306
FC0E3C
3EAE0008
move . w
8 ( A6) , (A7 )
Drive number
FC0E40
2 02EFFF4
move . 1
-12 ( A6) , DO
Error code
FC0E44
3F00
move . w
DO, - (A7)
as parameter
FC0E46
4EB900FC073E
jsr
$FC073E
critical error handler
FC0E4C
548F
addq . 1
#2 , A7
Correct stack pointer
FC0E4E
2D40FFF4
move . 1
DO, -12 (A6)
Save error code
FC0E52
202EFFF4
move . 1
-12 (A6) , DO
test
FC0E56
BOBCOOOIOOOO
cmp. 1
#$10000, DO
Retry ?
FC0E5C
67B0
beq
$FC0E0E
Yes, try again
FC0E5E
4AAEFFF4
tst . 1
-12 (A6)
Test error code
FC0E62
6C06
bge
$FC0E6A
OK ?
FC0E64
4280
clr.l
DO
FC0E66
60000124
bra
$FC0F8C
FC0E6A
2EBC00001685
move . 1
#$1685, (A7 )
Buffer+11, bytes per sectgor
FC0E70
610006BE
bsr
$FC1530
u2i, 8086 to 68000 format
FC0E74
3E00
move . w
DO, D7
Save bytes per sector
FC0E76
6F0E
ble
$FC0E86
< = 0, error
FC0E78
1C3900001687
move . b
$1687, D6
Buffer+13, sectors per cluster
FC0E7E
4886
ext.w
D6
FC0E80
CC7C00FF
and.w
#$FF,D6
FC0E84
6E06
bgt
$FC0E8C
> 0, OK
FC0E86
4280
clr.l
DO
0 as result
FC0E88
60000102
bra
$FC0F8C
Error
FC0E8C
3887
move . w
D7, (A4 )
recsize in bpb
FC0E8E
39460002
move . w
D6, 2 (A4)
clsiz in bpb
FC0E92
2EBC00001 690
move . 1
#$1690, (A7)
Buffer+22, sectors per FAT
FC0E98
61000696
bsr
$FC1530
u2i, 8086 to 68000 format
FC0E9C
39400008
move . w
DO, 8 ( A4 )
fsiz in bpb
FC0EA0
302C0008
move . w
8 ( A4 ) , DO
f siz
FC0EA4
5240
addq . w
#1 , DO
plus 1
Abacus Software Atari ST internals
FC0EA6
3940000A
move . w
DO, 10 ( A4 )
FCOEAA
3014
move . w
( A4 ) , DO
FC0EAC
C1EC0002
muls . w
2 ( A4 ) , DO
FC0EB0
39400004
move . w
DO, 4 ( A4 )
FC0EB4
2EBC0000168B
move . 1
#$1 68B, ( A7 )
FC0EBA
61000674
bsr
$FC1530
FC0EBE
EB40
asl.w
#5, DO
FC0EC0
48C0
ext . 1
DO
FC0EC2
81D4
divs . w
(A4 ) , DO
FC0EC4
39400006
move .w
DO, 6(A4)
FC0EC8
302C000A
move . w
10 (A4 ) , DO
FC0ECC
D06C0006
add.w
6 ( A4 ) , DO
FC0ED0
D06C0008
add.w
8 (A4 ) , DO
FC0ED4
3940000C
move . w
DO, 12 (A4 )
FC0ED8
2EBC0000168D
move . 1
#$168D, ( A7 )
FC0EDE
61000650
bsr
$FC1530
FC0EE2
906C000C
sub.w
12 ( A4 ) , DO
FC0EE6
48C0
ext . 1
DO
FC0EE8
81EC0002
divs .w
2 ( A4 ) , DO
FC0EEC
3940000E
move . w
DO, 14 ( A4 )
FC0EF0
2EBC00001694
move . 1
#$1694, ( A7 )
FC0EF6
61000638
bsr
$FC1530
FC0EFA
3B400014
move . w
DO, 20 (A5)
FC0EFE
2EBC00001692
move . 1
#$1692, ( A7 )
FC0F04
6100062A
bsr
$FC1530
FC0F08
3B400018
move . w
DO, 24 (A5)
FC0F0C
302D0014
move . w
20 (A5) , DO
FC0F10
C1ED0018
muls .w
24 (A5) , DO
FC0F14
3B400016
move . w
DO, 22 (A5)
FC0F18
2EBC00001696
move . 1
#$1696, (A7 )
FC0F1E
61000610
bsr
$FC1530
FC0F22
3B40001A
move . w
DO, 26 (A5)
as fatrec in bpb
recsize
times clsiz
as clsizb in bpb
Buffer+17, number of director entries
u2i, 8086 to 68000 format
times 32
by recsiz
as rdlen in bpb
fatrec
plus rdlen
plus fsiz
as datrec in bpb
Buffer+19, number of sectors
u2i, 8086 format to 68000 format
minus datrec
by clsiz
as numcl in bpb
Buffer+26, number of sides
u2i, 8086 to 68000 format
as dnsides in bpb
Buffer+24, sectors per track
u2i, 8086 to 68000 format
as dspt in bpb
dnsides
times dspt
as dspc in bpb
Buffer+28, number of hidden sectors
u2i, 8086 in 68000 format
as dhidden in bpb
Abacus Software Atari ST Internals
308
FC0F26 2EBC0000168D
FC0F2C 61000602
FC0F30 4 8C0
FC0F32 81ED0016
FC0F36 3B400012
FC0F3A 4247
FC0F3C 6016
FC0F3E 204D
FC0F40 3247
FC0F42 D1C9
FC0F44 3247
FC0F46 D3FC00001 67A
FC0F4C 11690008001C
FC0F52 5247
FC0F54 BE7C0003
FC0F58 6DE4
FC0F5A 207C000009B4
FC0F60 32 6E0008
FC0F64 D1C9
FC0F66 227C000009B2
FC0F6C 34 6E0008
FC0F70 D3CA
FC0F72 1091
FC0F74 6704
FC0F76 7001
FC0F78 6002
FC0F7A 4240
FC0F7C 227C00004DB8
FC0F82 34 6E0008
FC0F86 D3CA
FC0F88 1280
FC0F8A 200D
move . 1
#$1 68D, (A7 )
bsr
$FC1530
ext . 1
DO
divs . w
22 (A5) , DO
move . w
DO, 18 (A5)
clr . w
D7
bra
$FC0F54
move . 1
A5, A0
move . w
D7,A1
add. 1
Al, A0
move . w
D7,A1
add. 1
#$167A, Al
move . b
8 (Al ) , 28 (A0)
addq . w
#1, D7
cmp.w
#3, D7
bit
$FC0F3E
move . 1
#$9B4 , A0
move . w
8 (A6) , Al
add. 1
Al, A0
move . 1
#$9B2, Al
move . w
8 (A6) ,A2
add. 1
A2, Al
move . b
(Al) , (A0)
beq
$FC0F7A
moveq. 1
#1 , DO
bra
$FC0F7C
clr ,w
DO
move . 1
#$4DB8, Al
move . w
8 (A6) , A2
add. 1
A2, Al
move . b
DO, (Al)
move . 1
A5, DO
Buffer+19, number of sectors on disk
u2i , 8086 to 68000 format
by dspc
as dntracks in bpb
Counter to zero
Jump to loop end
Buffer pointer
Counter
plus buffer address
Counter
Address of disk buffer
Copy byte of serial number
Increment counter
already 3 ?
No
cdev
Drive
wpstatus
Drive
Diskette status uncertain
Status certain
Drive
Save status
Address of bpb as result
Abacus Software Atari ST internals
309
FC0F8C 4 A9F
FC0F8E 4CDF30C0
FC0F92 4E5E
FC0F94 4E75
tst . 1 (A7) +
movem.l ( A7 ) +, D6-D7 /A4-A5
unlk A6
rts
FC0F96 4E560000
FC0F9A 48E70304
FC0F9E OC6E00020008
FC0FA4 6D04
FC0FA6 7 0F1
FC0FA8 604C
FCOFAA 3E2E0008
FCOFAE 3A4 7
FCOFBO DBFC00004DB8
FC0FB6 0C150002
FCOFBA 6604
FCOFBC 7002
FCOFBE 6036
FCOFCO 2 07000000 9B4
FC0FC6 4A307000
FCOFCA 6704
FCOFCC 1ABC0001
FCOFDO 2039000004 BA
FC0FD6 3247
FC0FD8 D3C9
FCOFDA D3C9
FCOFDC D3FC000009B6
FC0FE2 2211
FC0FE4 9081
FC0FE6 B0B900002 9B4
FCOFEC 6C04
link A6, #0
movem.l D6-D7 /A5 , - (A7)
cmp.w #2, 8 (A6)
bit $FCOFAA
moveq.l #-15, DO
bra $FC0FF6
move . w 8 ( Ab) , D7
move.w D7,A5
add. 1 #$4DB8,A5
cmp.b #2, (A5)
bne $FC0FC0
moveq.l #2, DO
bra $FC0FF6
move . 1 #$9B4,A0
tst .b 0 (AO, D7 .w)
beq $FC0FD0
move ,b #1, (A5)
move . 1 $4BA,D0
move.w D7,A1
add.l A1,A1
add.l A1,A1
add.l #$9B6,A1
move . 1 (A1 ) , D1
sub. 1 Dl, DO
cmp.l $29B4,D0
bge $FC0FF2
Restore registers
mediach, disk changed?
Save registers
Drive number <21
Yes
'unknown device'
Error exit
Drive number
plus address of bpb
media changed, disk was changed
Error exit
wplatch
Test for drive
OK ?
Status uncertain
hz 200
maxacctim
Abacus Software Atari ST Internals
310
FCOFEE
4240
clr . w
DO
FC0FF0
6004
bra
$FC0FF6
FC0FF2
1015
move . b
(A5) , DO
FC0FF4
4880
ext . w
DO
FC0FF6
4A9F
tst . 1
(A7 ) +
FC0FF8
4CDF2080
movem . 1
(A7) + , D7/A5
FCOFFC
4E5E
unlk
A6
FCOFFE
4E75
rts
*****************************************************
FC1000
4E560000
link
>
O'!
=#=
o
FC1004
48E70F04
movem . 1
D4-D7/A5, - (A7)
FC1008
3C2E0008
move .w
8 (A6) ,D6
FC100C
3006
move .w
D6, DO
FC100E
EB4 0
asl.w
#5, DO
FC1010
4800
ext . 1
DO
FC1012
2A4 0
move . 1
DO, A5
FC1014
DBFC00004DCE
add. 1
#$4DCE,A5
FC101A
3E86
move . w
D6, (A7 )
FC101C
6100FF7 8
bsr
$FC0F96
FC1020
3E00
move . w
DO, D7
FC1022
BE7C0002
cmp.w
#2 , D7
FC1026
660A
bne
$FC1032
FC1028
3007
move . w
D7 , DO
FC102A
6000009C
bra
$FC10C8
FC102E
60000096
bra
$FC10C6
FC1032
BE7C0001
cmp.w
#1, D7
FC1036
6600008E
bne
$FC10C6
FC103A
3EBC0001
move . w
#1, ( A7 )
FC103E
4267
clr . w
-<A7)
FC1040
4267
clr . w
- (A7)
ok, disk wasn't changed
Get result
Restore registers
Test for disk change
Save registers
Drive number
times 32
plus address bpb
test media change
Changed ?
No
Diskette changed?
No
Read sector (boot sector)
Side 0
Track 0
Abacus Software Atari ST Internals
FC1042
3F3C0001
move . w
#1 , - ( A7 )
FC1046
3F06
move . w
D6,-(A7)
FC1048
42A7
clr.l
- (A7)
FC104A
2F3C0000167A
move . 1
#$167A,- (A7)
FC1050
4EB900FC159E
jsr
$FC159E
FC1056
DFFC00000010
add. 1
#S10,A7
FC105C
2A00
move . 1
DO , D5
FC105E
4A85
tst.l
D5
FC1060
6C10
bge
$FC1072
FC1062
3E86
move .w
D6, (A7)
FC1064
2005
move . 1
D5, DO
FC1066
3FOO
move . w
DO, - (A7)
FC1068
4EB900FC073E
jsr
$FC073E
FC106E
548F
addq . 1
#2 , A7
FC1070
2A00
move . 1
DO , D5
FC1072
BABC00010000
cmp. 1
#$10000, D5
FC1078
67C0
beq
$FC103A
FC107A
4A85
tst . 1
D5
FC107C
6C04
bge
$FC1082
FC107E
2005
move . 1
D5, DO
FC1080
6046
bra
$FC10C8
FC1082
4247
clr ,w
D7
FC1084
601C
bra
$FC10A2
FC1086
207C0000167A
move . 1
#$167A, A0
FC108C
10307008
move . b
8 (A0,D7.w) , DO
FC1090
4880
ext .w
DO
FC1092
1235701C
move . b
28 (A5, D7 . w) ,D1
FC1096
4881
ext .w
D1
FC1098
B04 1
cmp.w
Dl, DO
FC109A
6704
beq
$FC10AO
FC109C
7002
moveq. 1
#2, DO
Sector 1
Drive number
Filler
Address of disk buffer
f loprd
Correct stack pointer
Save error number
OK ?
Error number
Pass to critical error handler
Correct stack pointer
Error number
Retry ?
Yes, try again
Error code
OK ?
Else error number
Error exit
clear media change status
Address of disk buffer
Serial number
compare with old value
Match ?
Yes
Media changed
Abacus Software Atari ST Internals
312
FC109E 6028
bra
$FC10C8
FC10A0 5247
FC10A2 BE7C0003
FC10A6 6DDE
FC10A8 3046
FC10AA D1FC000009B4
FC10B0 3246
FC10B2 D3FC000009B2
FC10B8 1091
FC10BA 660A
FC10BC 3046
FC10BE D1FC00004DB8
FC10C4 4210
FC10C6 4240
FC10C8 4A9F
FC10CA 4CDF20E0
FC10CE 4E5E
FC10D0 4E75
addq.w #1,D7
cmp.w #3 , D7
bit $FC1086
move . w D6,A0
add. 1 #$ 9B4 , AO
move.w D6,A1
add. 1 #$9B2,A1
move . b (Al) , (AO)
bne $FC10C6
move.w D6,A0
add. 1 #$4DB8, AO
clr.b (AO)
clr.w DO
tst.l (A7)+
movem.l (A7) +, D5-D7/A5
unlk A6
rts
★★★★★★★★A******************
FC10D2 4E560000
FC10D6 48E70700
FC10DA 3E2E0012
FC10DE 3007
FC10E0 B07C0002
FC10E4 6D0 6
FC10E6 70F1
FC10E8 60000068
FC10EC 4A7 9000004A6
FC10F2 6604
;*************************+**
link A6, #0
movem.l D5-D7,-(A7)
move . w 18 (A6) , D7
move.w D7,D0
cmp.w #2, DO
bit $FC10EC
moveq.l #-15, DO
bra $FC1152
tst.w $4A6
bne $FC10F8
Error exit
next byte of serial number
All three bytes tested?
No
Drive number
wplatch
Drive number
wpstatus
accept
OK
Restore registers
rwabs, read/write sector (s)
Save registers
Drive number
Less than 2 ?
yes
'unknown device'
Error exit
_nflops, floppies connected?
Yes
Abacus Software Atari ST Internals
FC 1 OF 4
7 OFE
moveq . 1
O
Q
CM
1
FC10F6
605A
bra
$FC1 152
FC10F8
4 AAE000A
tst . 1
10 ( A6)
FC10FC
6616
bne
$FC1114
FC10FE
302E000E
move . w
14 (A6) , DO
FC 1102
227C00004DB8
move . 1
#$4DB8,A1
FC1108
34 6E0012
move . w
18 ( A6) ,A2
FC110C
D3CA
add. 1
A2 , A1
FC110E
1280
move .b
DO, (Al)
FC1110
4280
clr . 1
DO
FC1112
603E
bra
5FC1152
FC11 14
0C6E00O20008
cmp.w
#2,8 (A6)
FC111A
6C1C
bge
$FC1138
FC111C
3E87
move . w
D7 , (Al)
FC11 IE
6100FEE0
bsr
$FC1000
FC1122
4 8C0
ext . 1
DO
FC1124
2C00
move . 1
DO , D6
FC1126
4A86
tst . 1
D6
FC1128
670E
beq
$FC1138
FC112A
BCBC00000002
cmp. 1
#2 , D6
FC1130
6602
bne
$FC1134
FC11 32
7CF2
moveq . 1
#-14, D6
FC1134
2006
move . 1
D6, DO
FC1136
601A
bra
$FC1152
FC1138
3EAE000E
move . w
14 ( A6) , (Al)
FC113C
3F07
move . w
D7,-(A7)
FC113E
3F2E0010
move . w
16 (A6) ,- (A7)
FC1142
2F2E000A
move . 1
10 ( A6) ,- (A7)
FC1146
3F2E0008
move . w
8 (A6) , - (A7 )
'Drive not ready'
Error exit
buffer
Address specified?
count, number of sectors
Base address
Drive number
add
Sector counter
OK
Done
rwflag, ignore media change ?
Yes
Drive number
was disk changed?
Save error code
Not changed, OK
Definitely changed?
Yes
'Diskette was changed'
Error exit
count, number of sectors
Drive number
recno, first sector number
buffer
rwflag, read/write
I
Abacus Software Atari ST Internals
314
FC114A
6110
bsr
$FC1 15C
f loprw
FC114C
DFFC0000000A
add. 1
#$A, A7
Correct stack pointer
FC1152
4 A9F
tst . 1
(A7 ) +
FC1154
4CDF00C0
movem. 1
(A7 ) +, D6-D7
Restore registers
FC1158
4E5E
unlk
A6
FC115A
4E75
rts
******************************************,*************
floprw, read/write sect*
FC115C
4E56FFFA
link
VO
1
=#=
VO
<
FC11 60
48E73F04
movem . 1
D2-D7/A5, - (A7)
Restore registers
FC11 64
302E0010
move . w
16 (A6) , DO
Drive number
FC11 68
EB40
asl.w
#5, DO
times 32
FC116A
4 8C0
ext . 1
DO
FC116C
2A40
move . 1
DO, A5
FC116E
DBFC00004DCE
add. 1
#$4DCE,A5
plus base address bpb
FC1174
082EOOOOOOOD
btst
#0, 13 (A6)
Buffer address odd?
FC117A
6604
bne
$FC1180
Yes
FC117C
4240
clr ,w
DO
Clear odd flag
FC117E
6002
bra
SFC1182
FC1180
7001
moveq. 1
#1, DO
Set odd flag
FC1182
3D40FFFE
move . w
DO, -2 ( A6)
And save
FC1186
4A6D001 6
tst . w
22 (A5)
dspc set ?
FC118A
660A
bne
$FC1196
Yes
FC118C
7009
moveq. 1
#9, DO
Else use 9
FC118E
3B400016
move . w
DO, 22 (A5 )
as dspt
FC1192
3B400018
move . w
DO, 24 (A5)
and dspc
FC11 96
60000180
bra
$FC1318
to loop end
FC119A
4 A6EFFFE
t st . w
-2 (A6)
Odd flag set?
FC119E
6708
beq
$FC11A8
No
FC11A0
203C0000167A
move . 1
#$1 67 A, DO
Address of disk buffer
FC11A6
6004
bra
$FC11AC
Abacus Software Atari ST Internals
315
FC11A8
2 02EOOOA
move . 1
10 ( A6 ) , DO
FC11AC
2D40FFFA
move . 1
DO, -6 ( A6 )
FC11B0
3C2EOOOE
move . w
14 (A6) , D 6
FC11B4
4 8C6
ext . 1
D6
FC11B6
8DED001 6
divs . w
22 (A5) ,D6
FC11BA
382E000E
move . w
14 ( A6) ,D4
FC11BE
4 8C4
ext . 1
D4
FC11C0
89ED0016
divs . w
22 (A5) ,D4
FC11C4
4844
swap
D4
FC11C6
B86D0018
cmp. w
24 (A5) ,D4
FC11CA
6C04
bge
$FC 1 1D0
FC11CC
4245
clr . w
D5
FC11CE
6006
bra
$FC11D6
FC11D0
7A01
moveq . 1
#1 , D5
FC11D2
986D0018
sub.w
24 ( A5 ) ,D4
FC11D6
4A6EFFFE
tst .w
-2 (A6)
FC11 DA
6704
beq
$FC11E0
FC11DC
7601
moveq. 1
#1, D3
FC11DE
6018
bra
$FC11F8
FC11E0
302D0018
move . w
24 (A5) , DO
FC11E4
9044
sub.w
D4 , DO
FC11E6
B06E0012
cmp.w
18 (A6) , DO
FC11EA
6C08
bge
$FC1 1F4
FC11EC
362D0018
move . w
24 (A5) ,D3
FC11F0
9644
sub.w
D4,D3
FC11F2
6004
bra
$FC1 1F8
FC11F4
362E0012
move . w
18 ( A6) ,D3
FC11F8
5244
addq . w
#1 , D4
FC11FA
082E00000009
btst
#0, 9 ( A6)
FC1200
67000080
beq
$FC1282
FC1204
2 02EFFFA
move . 1
-6 (A6) , DO
FC1208
B0AE000A
cmp. 1
10 ( A6) , DO
Get buffer address
and save
recno, logical sector number
divided by dspc yields track number
recno, logical sector number
divided by dspc, sectors per track
Remainder of division as sector number
Compare with dspt
Greater than or equal?
Side 0
Side 1
Subtract dspt
Odd-flag set?
No
Set counter to one
dspt
minus sector number
Compare with number of sectors
Greater or equal?
dspt
minus sector number equals counter
Number of sectors as counter
Increment sector number (first sector # = 1)
Test rwflag
Read ?
Buffer pointer
Equals specified buffer address?
Abacus Software Atari ST Internals
316
FC120C
FC120E
FC1212
FC1216
FC121C
FC121E
FC1220
FC1222
FC1224
FC1226
FC122A
FC122C
FC1230
FC1236
FC123C
FC123E
FC1240
FC1242
FC1248
FC124A
FC124C
FC124E
FC1250
FC1252
FC1256
FC1258
FC125E
FC1264
FC126A
FC126C
6710
beq
$FC12 IE
Yes
2EAEFFFA
move . 1
-6(A6) , ( A7 )
Source address
2F2E000A
move . 1
10 (A6) (A7)
Destination address
4EB900FCOAD6
jsr
$FC0AD6
Fastcopy, copy sector
588F
addq . 1
#4 , A7
Correct stack pointer
3E83
move . w
D3, ( A7 )
Number of sectors
3F05
move . w
D5, - (A7)
Side
3F0 6
move . w
D6, - (A7)
Track
3F04
move . w
D4,-(A7)
Sector
3F2E0010
move . w
16 (A6) , - (A7)
Drive
42A7
clr . 1
- (A7)
Filler
2F2EFFFA
move . 1
-6(A6) ,-<A7)
Buffer
4EB900FC1 67C
jsr
$FC1 67C
flopwr, write sector (s)
DFFC00000010
add. 1
#$10, A7
Correct stack pointer
2E00
move . 1
DO, D7
Error code
4A87
tst . 1
D7
OK ?
663E
bne
$FC12 80
No
4A7 9000004 4 4
tst.w
$444
fverify, verify ?
6736
beq
$FC1280
No
3E83
move . w
D3, (A7 )
Number of sectors
3F05
move . w
D5,-(A7)
Side
3F06
move . w
D6,-(A7)
Track
3F04
move . w
D4,-(A7)
Sector
3F2E0010
move . w
16 ( A6) , - ( A7 )
Drive
42A7
clr. 1
- ( A7 )
Filler
2F3C00001 67A
move . 1
#$167A, - ( A7 )
Address of disk buffer
4EB900FC18CE
jsr
$FC18CE
flopver, verify sectors
DFFC00000010
add. 1
#$10, A7
Correct stack pointer
2E00
move . 1
DO , D7
Error code
4A87
tst . 1
D7
OK ?
Abacus Software Atari ST Internals
317
FC126E
6610
bne
$FC1280
FC1270
2EBC00001 67A
move . 1
#$ 1 67 A, ( A7 )
FC1276
610002B8
bsr
$FC1530
FC127A
4A4 0
tst . w
DO
FC127C
6702
beq
5FC1280
FC127E
7EF0
moveq. 1
#-l 6, D7
FC1280
603A
bra
$FC12BC
FC1282
3E83
move . w
D3, ( A7 )
FC1284
3F05
move . w
D5 , - ( A7 )
FC1286
3F06
move . w
D6, - (A7 )
FC1288
3F04
move . w
D4 , - (A7)
FC128A
3F2E0010
move . w
16 (A6) (A7)
FC128E
42A7
clr . 1
-<A7)
FC1290
2F2EFFFA
move . 1
-6<A6) ,-( A7)
FC1294
4EB900FC159E
jsr
$FC159E
FC129A
DFFC00000010
add. 1
#$10, A7
FC12A0
2E00
move . 1
DO , D7
FC12A2
202EFFFA
move . 1
-6 (A6) , DO
FC12A6
B0AE000A
cmp. 1
10 (A6) , DO
FC12AA
6710
beq
$FC12BC
FC12AC
2EAE000A
move . 1
10 (A6) , ( A7 )
FC12B0
2F2EFFFA
move . 1
-6 ( A6) , - (A7 )
FC12B4
4EB900FCOAD6
jsr
$FC0AD6
FC12BA
588F
addq . 1
#4 , A7
FC12BC
4 A87
tst . 1
D7
FC12BE
6C32
bge
$FC12F2
FC12C0
3EAE0010
move . w
16 ( A6) , ( A7 )
FC12C4
2007
move . 1
D7 , DO
FC12C6
3F00
move . w
DO, - (A7)
FC12C8
4EB900FC073E
jsr
$FC073E
FC12CE
548F
addq . 1
#2 , A7
FC12D0
2E00
move . 1
DO, D7
No
Address of the disk buffer
u2i, convert 8086 integer to 68000 format
Bad sector list
No errors during verify?
'Bad sectors'
Number of sectors
Side
Track
Sector
Drive
Filler
Buffer
floprd, read sector (s)
Correct stack pointer
Error code
Buffer used
Equals desired buffer?
Yes
Source address
Destination address
Fastcopy, copy sector
Correct stack pointer
No error?
OK
Drive number
Error code
critical error handler
Correct stack pointer
Save error code
Abacus Software Atari ST Internals
318
FC12D2
OC6E00020008
cmp . w
#2,8 ( A6)
rwflag, ignore media change ?
FC12D8
6C18
bge
$FC12F2
Yes
FC12DA
BEBC00010000
cmp. 1
#$10000, D7
Retry ?
FC12E0
6610
bne
$FC12F2
No
FC12E2
3EAE0010
move . w
16 ( A6) , (A7 )
Drive number
FC12E6
6100FD18
bsr
$FC1000
Diskette change ?
FC12EA
B07C0002
cmp . w
#2, DO
Definitely changed?
FC12EE
6602
bne
$FC12F2
No
FC12F0
7EF2
moveq . 1
#-14, D7
■media changed'
FC12F2
BEBC00010000
cmp . 1
#$10000, D7
Retry ?
FC12F8
6700FF00
beq
$FC1 1FA
Yes, try again
FC12FC
4A87
tst . 1
D7
Error code
FC12FE
6C04
bge
$FC1304
OK ?
FC1300
2007
move . 1
D7 , DO
Error code
FC1302
601E
bra
$FC1322
To error exit
FC1304
3003
move . w
D3, DO
Sector counter
FC1306
4 8C0
ext . 1
DO
FC1308
7209
moveq. 1
#9, D1
FC130A
E3A0
asl . 1
D1 , DO
times 512
FC130C
D1AE000A
add. 1
DO, 10 (A6)
Increment buffer address
FC1310
D76EOOOE
add.w
D3, 14 ( A6)
Logical sector number plus sector counter
FC1314
97 6E0012
sub.w
D3, 18 (A6)
Decrement number of sectors to process
FC1318
4A6E0012
tst.w
18 ( A6)
Still sectors to process?
FC131C
6600FE7C
bne
$FC119A
Yes
FC1320
4280
clr . 1
DO
OK
FC1322
4 A9F
tst . 1
(A7) +
FC1324
4CDF20F8
movem . 1
(A7 ) +, D3-D7/A5
Restore registers
FC1328
4E5E
unlk
A6
FC132A
4E7 5
rts
******************************************************** random, generate random numbers
FC132C 4E56FFFC link A6,#-4
Abacus Software Atari ST Internals
VO
FC1330
4 AB900002 9B8
tst . 1
$2 9B8
Last random number
FC1336
6616
bne
$FC134E
Not zero?
FC1338
2039000004 BA
move . 1
$4 BA, DO
_hz_200
FC133E
7210
moveq. 1
#16, D1
FC1340
E3A0
asl.l
D1 , DO
« 16
FC1342
80B9000004BA
or .1
$4 BA, DO
_h z_2 0 0
FC1348
23C000002 9B8
move . 1
DO, $29B8
Use as start value
FC134E
2F3CBB40E62D
move . 1
#3141592621, -<A7)
FC1354
2F3900002 9B8
move . 1
$29B8,-(A7)
Last random value
FC135A
4EB900FC4BE4
jsr
$FC4BE4
Long multiplication
FC1360
508F
addq . 1
#8 , A7
Correct stack pointer
FC1362
5280
addq . 1
#1 , DO
plus
FC1364
23C000002 9B8
move . 1
DO, $29B8
as new start value
FC136A
2 03 900002 9B8
move . 1
$2 9B8 , DO
Result
FC1370
E080
asr.l
#8, DO
» 8
FC1372
C0BC00FFFFFF
and. 1
#$FFFFFF, DO
Clear bits 24-31
FC1378
4E5E
unlk
A6
FC137A
4E75
rts
*******************************************************
hdv boot, load boot sector
FC137C
4E560000
link
A6, #0
FC1380
4 8E70300
movem . 1
D6-D7 , - (A7)
Save registers
FC1384
4EB900FCOAF8
jsr
$FC0AF8
hdv init, initialize drive
FC138A
4A7 9000004A6
tst .w
$4A6
nf lops
FC1390
6704
beq
$FC1396
No drive connected?
FC1392
7001
moveq. 1
#1 , DO
'couldn't load'
FC1394
6002
bra
$FC13 98
FC1396
7002
moveq. 1
#2, DO
'no drive'
FC1398
3E00
move . w
DO, D7
Save error
FC139A
4A79000004A6
tst .w
$4 A6
_nf lops
FC13A0
6744
beq
$FC13E6
No drive?
FC13A2
OC 79000200000446
cmp . w
#2, $446
bootdev
Abacus Software Atari ST Internals
320
FC13AA
6C3A
bge
$FC13E6
No diskette?
FC13AC
3EBC0001
move . w
#1, (A7)
One sector
FC13B0
42 67
clr . w
- (A7)
Side 0
FC13B2
42 67
clr . w
- <A7 )
Track 0
FC13B4
3F3C0001
move . w
#1,-(A7)
Sector 1
FC13B8
3F3 9000004 4 6
move . w
$446, -(A7)
bootdev
FC13BE
42A7
clr . 1
- ( A7 )
Filler
FC13C0
2F3C0000167A
move . 1
#$1 67A, - (A7 )
Address of disk buffer
FC13C6
4EB900FC159E
jsr
$FC159E
floprd, read sector
FC13CC
DFFC00000010
add. 1
#$10, A7
Correct stack pointer
FC13D2
4A80
tst . 1
DO
Error ?
FC13D4
6604
bne
$FC13DA
Yes
FC13D6
4247
clr .w
D7
Clear error code
FC13D8
600C
bra
$FC13E6
FC13DA
4A39000009B2
tst . b
$9B2
wpstatus
FC13E0
6604
bne
$FC13E6
FC13E2
7003
moveq. 1
#3, DO
' unreadable '
FC13E4
6024
bra
$FC140A
FC13E6
4A47
tst . w
D7
Error ?
FC13E8
6704
beq
$FC13EE
No
FC13EA
3007
move . w
D7 , DO
Get error code
FC13EC
601C
bra
$FC140A
FC13EE
3EBC0100
move . w
#$100, (A7)
$100 words
FC13F2
2F3C0000167A
move . 1
#$167A, - (A7 )
Address of disk buffer
FC13F8
61000106
bsr
$FC1500
Calculate checksum
FC13FC
588F
addq . 1
#4 , A7
Correct stack pointer
FC13FE
B07C1234
cmp . w
#$1234, DO
magic for boot sector?
FC1402
6604
bne
$FC1408
No
FC1404
4240
clr .w
DO
OK
FC1406
6002
bra
$FC140A
FC1408
7004
moveq . 1
#4, DO
'not valid boot sector
FC140A
4A9F
tst . 1
(A7 ) +
Abacus Software Atari ST Internals
FC140C
4CDF0080
movem . 1
(A7 ) +, D7
FC1410
4E5E
unlk
A6
FC1412
4 E75
rts
**************************************************.
FC1414
4E56FFFA
link
A6,#-6
FC1418
48E70704
movem . 1
D5-D7/A5, - (A7)
FC141C
4A6E0012
tst .w
18 (A6)
FC1420
6C1E
bge
$FC1440
FC1422
3EBC0100
move . w
#$100, (A7 )
FC1426
2F2E0008
move . 1
8 (A6) , - (A7)
FC142A
610000D4
bsr
$FC1500
FC142E
588F
addq . 1
#4 , A7
FC1430
B07C1234
cmp.w
#$1234, DO
FC1434
6704
beq
$FC143A
FC1436
4240
clr .w
DO
FC1438
6002
bra
$FC143C
FC143A
7001
moveq . 1
#1 , DO
FC143C
3D400012
move . w
DO, 18 (A6)
FC1440
4AAE000C
tst . 1
12 ( A6)
FC1444
6D3E
bit
$FC14 84
FC1446
2 02E000C
move . 1
12 ( A6) , DO
FC144A
B0BC00FFFFFF
cmp. 1
#$FFFFFF, DO
FC1450
6F08
ble
$FC145A
FC1452
6100FED8
bsr
$FC132C
FC1456
2D40000C
move . 1
DO, 12 ( A6)
FC145A
4247
clr .w
D7
FC145C
6020
bra
$FC147E
FC145E
2 02E000C
move . 1
12 ( A6) , DO
FC1462
C0BC000000FF
and. 1
#$FF, DO
FC1468
3247
move . w
D7 , A1
FC146A
D3EE0008
add. 1
8 (A6) , A1
Restore registers
proto_bt, generate boot sector
Restore registers
Test execflg
Preserve executability
$100 words
Address of the sector buffer
Calculate checksum
Correct stack pointer
magic for boot sector?
Yes
Not executable
Executable
execflg
Serial number
Negative, don't change
Serial number
> $FFFFFF ?
No
rand, create random number
as serial number
Clear counter
Serial number
Bits 0-7
Pointer to next byte in buffer
plus buffer address
Abacus Software Atari ST Internals
322
FC146E
13400008
move . b
DO, 8 (Al)
FC1472
2 02E000C
move . 1
12 { A 6 ) , DO
FC1476
E080
asr . 1
#8, DO
FC1478
2D40000C
move . 1
DO, 12 (A6)
FC147C
5247
addq . w
#1 , D7
FC147E
BE7C0003
cmp.w
#3, D7
FC1482
6DDA
bit
$FC145E
FC1484
4A6E0010
tst .w
16 (A6)
FC1488
6D28
bit
$FC14B2
FC148A
3C2E0010
move . w
16 (A6) ,D6
FC148E
CDFC0013
muls .w
#$13, D6
FC1492
4247
clr.w
D7
FC1494
6016
bra
$FC14AC
FC1496
3047
move , w
D7, A0
FC1498
D1EE0008
add. 1
8 (A6) , A0
FC149C
3246
move . w
D6, Al
FC149E
D3FC00FD1B60
add. 1
#$FD1B60 , Al
FC14A4
1151000B
move . b
(Al) ,11 (A0)
FC14A8
5246
addq . w
#1 , D6
FC14AA
5247
addq . w
#1, D7
FC14AC
BE7C0013
cmp . w
#$13, D7
FC14B0
6DE4
bit
$FC1496
FC14B2
426EFFFA
clr.w
-6 ( A6)
FC14B6
2D6E0008FFFC
move . 1
8 (A6) , -4 (A6)
FC14BC
600E
bra
$FC14CC
FC14BE
206EFFFC
move . 1
-4 ( A6) , A0
FC14C2
3010
move . w
(A0) , DO
FC14C4
D16EFFFA
add.w
DO, -6 (A6)
FC14C8
54AEFFFC
addq . 1
#2,-4 (A6)
FC14CC
202E0008
move . 1
8 ( A6) , DO
FC14D0
D0BC000001FE
add. 1
#$1FE, DO
FC14D6
B0AEFFFC
cmp. 1
-4 ( A6) , DO
Byte of the serial number in buffer
Serial number
» 8
Increment counter
already 3 ?
No
Disk size
Negative, don't change
Disk size
times 19 equals pointer to prototype bpb
Clear counter
Counter
plus buffer address
Disk size
plus address of the prototype bpb
Copy bpb
Increment counter
already 19 ?
No
Buffer address
Buffer address
Get word from buffer
Add to checksum
Next word
Buffer address
plus $1FE
Last word?
Abacus Software Atari ST Internals
323
FC14DA
62E2
bhi
$FC 1 4 BE
No
FC14DC
303C1234
move . w
#$1234, DO
Checksum for boot sector
FC14E0
906EFFFA
sub . w
-6 (A6) , DO
subtract from previous value
FC14E4
226EFFFC
move . 1
-4 (A6) , A1
FC14E8
3280
move . w
DO, (Al)
Checksum in buffer
FC14EA
4 A6E0012
tst . w
18 ( A6)
execf lg
FC14EE
6606
bne
$FC14F6
Boot sector executable?
FC14F0
206EFFFC
move . 1
-4 ( A6) , A0
FC14F4
5250
addq . w
#1, (A0)
Increment checksum, not executable
FC14F6
4 A9F
tst . 1
<A7) +
FC14F8
4CDF20C0
movem . 1
(A7 ) +, D6-D7 / A5
Restore registers
FC14FC
4E5E
unlk
A6
FC14FE
4E75
rts
********************************************************
Calculate checksum
FC1500
4E560000
link
A6, #0
FC1504
4 8E70300
movem. 1
D6-D7 , - ( A7 )
Restore registers
FC1508
4247
clr .w
D7
Clear sum
FC150A
600C
bra
$FC1518
To loop end
FC150C
206E0008
move . 1
8 ( A6) , A0
Address of the buffer
FC1510
3010
move . w
(A0) , DO
Get word
FC1512
DE4 0
add.w
DO, D7
sum
FC1514
5 4 AE 000 8
addq . 1
#2 , 8 (A6)
Increment buffer address
FC1518
302E000C
move . w
12 ( A6) , DO
Number of words
FC151C
536EOOOC
subq . w
#1 , 12 ( A6)
minus 1
FC1520
4A40
tst . w
DO
All words added?
FC1522
66E8
bne
$FC150C
No
FC1524
3007
move . w
D7 , DO
Result to DO
FC1526
4 A9F
tst . 1
<A7) +
FC1528
4CDF0080
movem . 1
(A7 ) +,D7
Restore registers
FC152C
4E5E
unlk
A6
FC152E
4E75
rts
Abacus Software Atari ST Internals
324
******************************************************** u2i, 8086 integer to 68000 format
FC1530
4E56FFFC
link
A6, #— 4
FC1534
2 0 6E0008
move . 1
8 ( A6) , A0
Address of the number
FC1538
10280001
move . b
1 (A0) , DO
Hi byte
FC153C
4880
ext . w
DO
FC153E
C07C00FF
and. w
#$FF , DO
Isolate bits 0-7
FC1542
E140
asl . w
#8, DO
Shift to bits 8-15
FC1544
22 6E0008
move . 1
8 (A6) , A1
Address of the number
FC1548
1211
move . b
(Al) ,D1
Gte lo-byte
FC154A
4881
ext . w
D1
FC154C
C27C00FF
and.w
#$FF, D1
Isolate bits 0-7
FC1550
8041
or . w
D1 , DO
Combine with high byte
FC1552
4E5E
unlk
A6
FC1554
4E75
rts
********************************************************
flopini, initialize drive
FC1556
43F900000A06
lea
$A0 6, Al
Address of dsbO
FC155C
4 A6F000C
tst . w
12 (A7)
Drive A ?
FC1560
6706
beq
$FC1568
Yes
FC1562
43F900000A0A
lea
$A0A, Al
Else address of dsbl
FC1568
3379000004400002
move . w
$440,2 (Al)
Seek rate in dsb
FC1570
70FF
moveq. 1
#-l, DO
Default error number
FC1572
42690000
clr .w
(Al)
Track number to zero
FC1576
61 000 4 BC
bsr
$FC1A34
floplock, set parameters
FC157A
61000698
bsr
$FC1C1 4
select, select drive and side
FC157E
337CFF000000
move . w
#$FF00, (Al)
Track number negative, invalid
FC1584
6100061A
bsr
$FC1BA0
restore, track zero
FC1588
670C
beq
$FC1596
OK, flopok
FC158A
7E0A
moveq . 1
#10, D7
Track 10
FC158C
610005AO
bsr
$FC1B2E
hseek, find track
FC1590
6608
bne
$FC159A
Error, flopfail
FC1592
6100060C
bsr
$FC1BA0
restore
Abacus Software Atari ST Internals
FC1596 67000542 beq $FC1ADA OK, flopok
FC159A 60000530 bra $FC1ACC flopfail
FC159E
6100071E
FC15A2
7 0F5
FC15A4
6100048E
FC15A8
6100066A
FC15AC
610005CC
FC15B0
66000090
FC15B4
33FCFFFF000009E0
FC15BC
3CBC0090
FC15C0
3CBC0190
FC15C4
3CBC0090
FC15C8
33ED09CAFFFF8604
f . A
FC15D0
3CBC0080
FC15D4
3E3C0090
l/i
FC15D8
610006B6
FC15DC
2E3C0004 0000
FC15E2
2 4 6D0 9D0
FC15E6
08390005FFFFFA01
FC15EE
6734
FC15F0
5387
FC15F2
6724
FC15F4
1B79FFFF860909DB
FC15FC
1B7 9FFFF860B0 9DC
FC1604
1B79FFFF860D09DD
FC160C
B5ED09DA
FC1610
6ED4
FC1612
610005E6
FC1616
600C
FC1618
3B7CFFFE09E0
bsr
$FC1CBE
moveq . 1
#-11, DO
bsr
$FC1A34
bsr
$FC1C14
bsr
$FC1B7A
bne
$FC1 64 2
move . w
#-l,$9E0
move . w
#$90, (A6)
move . w
#$190, (A6)
move . w
#$90, (A6)
move.w
$9CA(A5) , $FFFF8604
move . w
#$80, (A6)
move . w
#$90, D7
bsr
$FC1C90
move . 1
#$40000, D7
move . 1
$9D0 (A5) ,A2
btst
#5, $FFFFFA01
beq
$FC1 62 4
subq. 1
#1 , D7
beq
$FC1618
move . b
$FFFF8609,$9DB(A5)
move . b
$FFFF860B, $9DC (A5)
move . b
$FFFF860D, $9DD (A5)
cmp . 1
$9DA(A5) ,A2
bgt
$FC15E6
bsr
$FC1BFA
bra
$FC1624
move . w
#-2,$9E0(A5)
floprd, read sector (s) from disk
change, test for disk change
Read error as error number
f loplock, set parameters
select, select drive and side
go2track, find track
Try again if error
General error
Clear DMA status, select read
ccount, sector counter
Select 1772
Read multiple sectors
wdiskctl, pass D7 to 1772
Timeout counter
edma, end address for DMA
mfp gpip, 1772 done ?
Yes
Decrement counter
Timeout ?
DMA address
End address reached?
No
reset, end transfer
Drive not ready
Abacus Software Atari ST Internals
326
FC161E
610005DA
bsr
$FC1BFA
reset, end transfer
FC1622
601E
bra
$FC1642
FC1624
3CBC0090
move . w
#$90, (A6)
Select DMA status register
FC1628
3016
move . w
(A6) , DO
Read status
FC162A
08000000
btst
#0, DO
DMA error ?
FC162E
6712
beq
$FC1642
Yes, try again
FC1630
3CBC0080
move . w
#$80, (A6)
Select 1772
FC1634
6100066E
bsr
$FC1CA4
rdiskctl, read status register
FC1638
C03C0018
and. b
#$18, DO
Isolate RNF, CRC and Lost Data
FC163C
6700049C
beq
$FC1ADA
No error, flopok
FC1640
6118
bsr
$FC1 65A
errbits, determine error number
FC1642
0C6D000109B0
cmp.w
#1 , $ 9B0 (A5)
retrycnt to second attempt?
FC1648
6604
bne
$FC164E
No
FC164A
610004FA
bsr
$FC1B4 6
ressek, home and seek
FC164E
536D09B0
subq.w
#1, $9B0 (A5)
Decrement retrycnt
FC1652
6A00FF54
bpl
$FC15A8
Another attempt?
FC1656
60000474
bra
$FC1ACC
No, flopfail
********************************************************
errbits, create floppy error number
FC165A
72F3
moveq . 1
#-13, D1
Diskette write-protected
FC165C
08000006
btst
#6, DO
Write protect ?
FC1660
6614
bne
$FC1 67 6
Yes
FC1662
72F8
moveq. 1
#-8,Dl
Sector not found
FC1664
08000004
btst
#4, DO
Sector not found ?
FC1668
660C
bne
$FC1 67 6
Yes
FC166A
72FC
moveq . 1
#-4,Dl
CRC Error
FC166C
08000003
btst
#3, DO
CRC Error ?
FC1670
6704
beq
$FC1 67 6
No
FC1672
322D09DE
move . w
$9DE ( A5) ,D1
Default error
FC1676
3B4109E0
move . w
Dl, $9E0 (A5)
FC167A
4E75
rts
Abacus Software Atari ST Internals
327
FC167C
61000640
bsr
$FC1CBE
change, test for disk change
FC1680
70F6
moveq . 1
#-10, DO
Write error as default error
FC1682
610003B0
bsr
5FC1A34
floplock, set parameters
FC1686
3 02 DO 9C 6
move . w
$9C6 ( A5) , DO
csect, sector number 1 ?
FC168A
5340
subq.w
#1 , DO
FC168C
806D09C4
or .w
$9C4 ( A5) , DO
ctrack, track number 0
FC1690
806D09C8
or .w
$9C8 ( A5) , DO
cside, side 0 ?
FC1694
6606
bne
$FC169C
No, not boot sector
FC1696
7002
moveq . 1
#2, DO
media change
FC1698
6100065C
bsr
$FC1CF6
Set to 'unsure'
FC169C
61000576
bsr
$FC1C14
select, select track and side
FC16A0
610004D8
bsr
$FC1B7A
go2track, find track
FC16A4
6600007E
bne
$FC1724
Error, try again
FC16A8
3B7CFFFF09E0
move . w
#-l,$9E0(A5)
currerr to default
FC1 6AE
3CBC0190
move . w
#$190, (A6)
FC16B2
3CBC0090
move . w
#$90, ( A6)
Clear DMA status, to write
FC16B6
3CBC0190
move . w
#$190, (A6)
FC16BA
3E3C0001
move . w
#1 , D7
Sector count register
FC16BE
610005D0
bsr
$FC1C90
wdiskctl, D7 to 1772
FC16C2
3CBC0180
move . w
#$180, (A6)
Select 1772
FC16C6
3E3C00A0
move . w
#$A0,D7
Write sector
FC16CA
610005C4
bsr
$FC1C90
wdiskctl, D7 to 1772
FC16CE
2E3C0004 0000
move . 1
#$40000, D7
Timeout counter
FC16D4
08390005FFFFFA01
btst
#5, $FFFFFA01
mfp gpip, 1772 done ?
FC16DC
670A
beq
$FC1 6E8
Yes
FC16DE
5387
subq . 1
#1,D7
Decrement timeout counter
FC16E0
66F2
bne
$FC1 6D4
Timeout?
FC16E2
61000516
bsr
$FC1BFA
reset, terminate transfer
FC16E6
6034
bra
$FC171C
Next try
FC16E8
3CBC0180
move . w
#$180, (A6)
Select 1772
Abacus Software Atari ST Internals
FC16EC
610005B6
bsr
$FC1CA4
rdiskctl, read status register
FC16F0
6100FF68
bsr
$FC165A
errbits, calculate error number
FC16F4
08000006
btst
#6, DO
write protect ?
FC16F8
660003D2
bne
$FC1ACC
flopfail, no further attempt
FC16FC
C03C005C
and. b
#$5C, DO
write protect, RNF, CRC and Lost Data
FC1700
661A
bne
5FC171C
Error, try again
FC1702
526D09C6
addq . w
#1, $9C6 (A5)
csect, increment sector number
FC1706
06AD0000020009CC
add. 1
#512, $9CC (A5)
cdma, DMA address to next sector
FC170E
536D09CA
subq.w
#1, $9CA (A5)
ccount, decrement number of sectors
FC1712
670003C6
beq
$FC1ADA
All sectors, done, flopok
FC1716
61000524
bsr
$FC1C3C
selectl, sector number and DMA pointer
FC171A
608C
bra
$FC16A8
Write next sector without seek
FC171C
0C6D0O0109B0
cmp.w
#1, $9B0 (A5)
retrycnt, second try?
FC1722
6604
bne
$FC1728
No
FC1724
61000420
bsr
$FC1B4 6
reseek, home and seek
FC1728
536D09B0
subq.w
#1, $9B0 (A5)
retrycnt, decrement try counter
FC172C
6A00FF6E
bpl
$FC169C
Another try?
FC1730
6000039A
bra
$FC1ACC
No, flopfail
********************************************************
flopfmt, format track
FC1734
0CAF87 654 321001 6
cmp. 1
#$87654321,22 (A7)
Magic number ?
FC173C
6600038E
bne
$FC1ACC
No, flopfail
FC1740
6100057C
bsr
$FC1CBE
change, test for disk change
FC1744
7 OFF
moveq. 1
#-l , DO
Default Error Nummer
FC1746
610002EC
bsr
$FC1A34
floplock, set parameters
FC174A
610004C8
bsr
$FC1C14
select, select drive and side
FC174E
3B6F000E09D4
move . w
14 (A7) , $9D4 (A5)
spt, sectors per track
FC1754
3B6F001409D6
move .w
20 ( A7 ) , $9D6 ( A5)
interlv, interleave factor
FC175A
3B6F001A0 9D8
move . w
26 (hi) , $9D8 (A5)
virgin, sector data for formatting
FC1760
7002
moveq . 1
#2, DO
'changed'
FC1762
61000592
bsr
$FC1CF6
Diskette changed
FC1766
610003C0
bsr
$FC1B2 8
hseek, search for track
Abacus Software Atari ST Internals
Gb
N>
VO
FC176A 66000360
FC176E 336D09C40000
FC1774 3B7CFFFF09E0
FC177A 6128
FC177C 6600034E
FC1780 3B6D09D409CA
FC1786 3B7C000109C6
FC178C 6100015C
FC1790 246D09CC
FC1794 4A52
FC1796 67000342
FC179A 3B7CFFF009EO
FC17A0 6000032A
***************************
FC17A4 3B7CFFF609DE
FC17AA 363C0001
FC17AE 24 6D09CC
FC17B2 323C003B
FC17B6 103C004E
FC17BA 6100010A
FC17BE 3803
FC17C0 323C000B
FC17C4 4200
FC17C6 610000FE
FC17CA 323C0002
FC17CE 103C00F5
FC17D2 610000F2
FC17D6 14FC00FE
FC17DA 14F9000009C5
FC17E0 14F9000009C9
FC17E6 14C4
bne
$FC1ACC
move . w
$9C4 ( A5) , (Al)
move . w
#-l, $9E0 ( A5 )
bsr
$FC17A4
bne
$FC 1ACC
move . w
$9D4 ( A5) , $9CA(A5)
move . w
#1, $9C6(A5)
bsr
$FC18EA
move . 1
$9CC(A5) ,A2
tst .w
(A2 )
beq
$FC1ADA
move . w
#-16,$9E0(A5)
bra
$FC1ACC
**************************
move . w
#-10,$9DE(A5)
move . w
#1 , D3
move . 1
$9CC(A5) ,A2
move . w
#$3B,D1
move . b
#$4E, DO
bsr
$FC18C6
move . w
D3,D4
move . w
#$B,D1
clr .b
DO
bsr
$FC18C6
move . w
#2 , D1
move . b
#$F5 , DO
bsr
$FC18C6
move . b
#$FE, (A2 ) +
move .b
$9C5, (A2 ) +
move . b
$9C9, ( A2 ) +
move . b
D4 , (A2)+
Not found, flopfail
ctrack, write current track in DSB
General error
Format track
flopfail, error
spt sectors per track as ccount counter
csect, start with sector 1
verify, verify sector
cdma, list with bad sectors
Bad sector?
No, flopok
Bad sectors
flopfail, error
fmtrack, format track
Write error
Start with sector 1
cdma, buffer for track data
60 times
$4E, track header
wmult, write in buffer
Save sector number
12 times
0
wmult, write in buffer
3 times
$F5
wmult, write in buffer
$FE, address mark
Track
Side
Sector
Abacus Software Atari ST Internals
330
FC17E8 14FC0002
FC17EC 1 4FC00F7
FC17F0 323C0015
FC17F4 103C004E
FC17F8 610000CC
FC17FC 323COOOB
FC1800 4200
FC1802 610000C2
FC1806 323C0002
FC180A 1O3C00F5
FC180E 610000B6
FC1812 14FC00FB
FC1816 323C00FF
FC181A 14ED09D8
FC181E 14ED09D9
FC1822 51C9FFF6
FC1826 14FC00F7
FC182A 323C0027
FC182E 103C004E
FC1832 61000092
FC1836 D86D09D6
FC183A B86D09D4
FC183E 6F80
FC1840 5243
FC1842 B66D09D6
FC1846 6F00FF7 6
FC184A 323C0578
FC184E 103C004E
FC1852 6172
FC1854 13ED09CFFFFF860D
FC185C 13ED09CEFFFF860B
FC1864 13ED09CDFFFF8609
move . b
#2, (A2 ) +
move .b
#$F7 , ( A2 ) +
move . w
#S15,D1
move .b
#$4E, DO
bsr
$FC18C6
move . w
#$B,D1
clr.b
DO
bsr
$FC18C6
move . w
#2 , D1
move . b
#$F5, DO
bsr
SFC18C6
move . b
#$FB, (A2 ) +
move . w
#$FF,D1
move . b
$9D8 (A5) , ( A2 ) +
move . b
$9D9(A5) , ( A2 ) +
dbra
Dl, $FC181A
move . b
#$F7 , (A2 ) +
move.w
#$27, Dl
move . b
#$4E, DO
bsr
$FC18C6
add.w
$9D6(A5) ,D4
cmp. w
$9D4 ( A5) ,D4
ble
$FC17C0
addq . w
#1, D3
cmp.w
$9D6(A5) ,D3
ble
$FC17BE
move . w
#$578, Dl
move . b
#$4E, DO
bsr
$FC18C6
move . b
$9CF (A5) , $FFFF860D
move . b
$9CE (A5) , $FFFF860B
move . b
$9CD (A5) , SFFFF8609
Sector size 512 bytes
Write checksum
22 times
$4E
wmult, write in buffer
12 times
0
wmult, write in buffer
3 times
$F5
wmult, write in buffer
$FB, data block mark
256 times
virgin, initial data in buffer
Next word
Write checksum
40 times
$4E
wmult, write in buffer
Add interlv, next sector
spt, largest sector number
No, next sector
Start sector plus one
interlv
Next sector
1401 times (until track end)
$4E
wmult, write in buffer
dmalow
dmamid
dmahigh
Abacus Software Atari sx Internals
FC186C 3CBC0190
FC1870 3CBC0090
FC1874 3CBC0190
FC 1878 3E3C001F
FC187C 61000412
FC1880 3CBC0180
FC1884 3E3C00F0
FC1888 61000406
FC188C 2E3C00040000
FC1892 08390005FFFFFA01
FC18 9A 67 0C
FC189C 5387
FC189E 66F2
FC18A0 61000358
FC18A4 7E01
FC18A6 4E75
CO
u>
“ FC18A8 3CBC0190
FC18AC 3016
FC18AE 08000000
FC18B2 67F0
FC18B4 3CBC0180
FC18B8 610003EA
FC18BC 6100FD9C
rC18C0 C03C0044
FC18C4 4E75
FC18C6 14C0
FC18C8 51C9FFFC
FC18CC 4E75
move.w #$190, (A6)
move . w #$90, ( A6)
move.w #$190, (A6)
move.w #$1F,D7
bsr $FC1C90
move.w #$180, (A6)
move.w #$F0,D7
bsr $FC1C90
move.l #$40000, D7
btst #5, $FFFFFA01
beq $FC18A8
subq.l #1,D7
bne $FC1892
bsr $FC1BFA
moveq.l #1,D7
rts
move.w #$190, (A6)
move.w (A6) , DO
btst #0,D0
beq $FC18A4
move.w #$180, (A6)
bsr $FC1CA4
bsr $FC165A
and.b #$44, DO
rts
move .b DO, (A2) +
dbra D1,$FC18C6
rts
*******************************
Clear DMA status, write
Sector counter to 31
wdiskctl, send D7 to 1772
Select 1772
Format Track command
wdiskctl, send D7 to 1772
Timeout counter
mfp gpip, 1772 done ?
Yes
Decrement timeout counter
Run out?
Reset, terminate
Clear Z-bit, error
Select DMA status
Read status
DMA error ?
Yes, error
Select 1772 status register
rdiskctl, read register
errbits, calculate error number
Test write protect and lost data
Write byte in buffer
Next byte
flopver, verify sector (s)
Abacus Software Atari ST Internals
FC18CE 610003EE
bsr
$FC1CBE
change, test for disk change
cr
FC18D2 70F5
moveq .
1 #-11, DO
Read error as default error
83
n
FC18D4 6100015E
bsr
$FC1A34
floplock, set parameter
c
FC18D8 6100033A
bsr
$FC1C14
select
03
/-s
FC18DC 6100029C
bsr
$FC1B7A
go2track, find track
W
»
FC18E0 660001EA
bne
$FC1 ACC
flopfail, error
63
FC18E4 6104
bsr
$FC18EA
verifyl, verify sectors
ft
FC18E6 600001F2
bra
$FC1ADA
flopok, done
***************************
*****************************
verifyl
FC18EA 3B7CFFF509DE
move . w
#-ll,$9DE(A5)
Read error
FC18F0 24 6D09CC
move . 1
$9CC (A5) ,A2
cdma, DMA buffer for bad-sector list
FC18F4 06AD0000020009CC
add. 1
#512, $9CC ( A5 )
cmda to next sector
FC18FC 3B7C000209BO
move . w
#2, $9B0 ( A5 )
retrycnt, 2 tries
FC1902 3CBC0084
move . w
#$84, (A6)
Select sector register
u>
FC1906 3E2D09C6
move ,w
$9C6 (A5) ,D7
csect, sector number
Ol
K)
FC190A 61000384
bsr
$FC1C90
wdiskctl, D7 to 1772
FC190E 13ED09CFFFFF860D
move . b
$9CF(A5) ,$FFFF860D
FC1916 13ED09CEFFFF860B
move . b
$9CE (A5) , $FFFF860B
Set DMA address
FC191E 13ED09CDFFFF8609
move . b
$9CD(A5) , $FFFF8609
FC1926 3CBC0090
move . w
#$90, ( A6)
FC192A 3CBC0190
move . w
#$190, (A6)
Clar DMA status, read
FC192E 3CBC0090
move . w
#$90, (A6)
FC1932 3E3C0001
move . w
#1, D7
Sector counter to 1
FC1936 61000358
bsr
$FC1C90
wdiskctl, D7 to 1772
FC193A 3CBC0080
move . w
#$80, (A6)
Select 1772 command register
>
FC193E 3E3C0080
move . w
#$80, D7
Read Sector command
63
>1
FC1942 6100034C
bsr
$FC1C90
wdiskctl, D7 to 1772
03
FC1946 2E3C00040000
move . 1
#$40000, D7
Timeout counter
H
FC194C 083 90005FFFFFA01
btst
#5, $FFFFFA01
mfp gpip, 1772 done?
HH
a
FC1954 670A
beq
$FC1 960
Yes
ft
FC1956 5387
subq. 1
#1 , D7
Decrement timeout counter
a
a
FC1958
66F2
bne
$FC1 94C
FC195A
610002 9E
bsr
5FC1BFA
FC195E
6036
bra
$FC1996
FC1960
3CBC0090
move . w
#$90, ( A6)
FC1964
3016
move . w
(A6) , DO
FC1966
08000000
btst
#0, DO
FC196A
67 2 A
beq
$FC1996
FC196C
3CBC0080
move . w
#$80, ( A6)
FC1970
61000332
bsr
$FC1CA4
FC1974
6100FCE4
bsr
$FC1 65A
FC1978
C03C001C
and.b
#$1C, DO
FC197C
6618
bne
$FC1996
FC197E
52 6D09C6
addq . w
#1, $9C6 (A5)
FC1982
536D09CA
subq.w
#1, $9CA(A5)
FC1986
6600FF7 4
bne
$FC18FC
FC198A
04AD0000020009CC
sub. 1
#512, $9CC (A5)
FC1992
4252
clr .w
(A2 )
FC1994
4E7 5
rts
i,nl ; i&3 ;
FC1996
OC6D000109BO
cmp.w
#1, $9B0 (A5)
FC199C
6604
bne
$FC1 9A2
FC199E
610001A6
bsr
$FC1B4 6
FC19A2
536D09B0
subq.w
#1, $9B0 (A5)
FC19A6
6A00FF66
bpl
$FC190E
FC19AA
34ED09C6
move . w
$9C6(A5) , (A2)+
FC19AE
60CE
bra
$FC197E
**************************************************’
FC19B0
9BCD
sub. 1
A5, A5
FC19B2
4DF9FFFF8606
lea
$FFFF8606, A6
FC19B8
50ED09BE
st
$9BE(A5)
FC19BC
4 A6D043E
tst .w
$43E(A5)
FC19C0
6670
bne
$FC1A32
Run out?
Reset 1772, terminate transfer
Next try
Select DMA status register
Read status
DMA error ?
Yes, try again
Select 1772 status register
rdiskctl, read status
errbits, calculate error number
Test RNF, CRC and Lost Data
Error next try
csect, next sector
ccount, decrement sector counter
Another sector?
cdma, reset DMA pointer
Terminate bad sector list with zero
retrycnt,2nd try?
No
reseek, home and seek
Decrement retrycnt
Another try?
csect, sector number in bad sector list
Next sector
flopvbl. Floppy Vertical Blank Handler
Clear A5
Address of the floppy register
Set motor on flag
flock, floppies active ?
Yes, do nothing
Abacus Software Atari ST Internals
334
FC19C2 2039000004 66
FC19C8 1200
FC19CA C23C0007
FC19CE 6638
FC19D0 3CBC0080
FC19D4 E608
FC19D6 C07C0001
FC19DA 41ED09B2
FC19DE D0C0
FC19E0 B07 9000004A6
FC19E6 6602
FC19E8 4240
FC19EA 5200
FC19EC E308
FC19EE 0AO00007
FC19F2 6100026C
FC19F6 3039FFFF8604
FC19FC 08000006
FC1AOO 56D0
FC1A02 1002
FC1A04 6100025A
FC1A08 302D09B2
FC1A0C 816D09B4
FC1A10 4A6D09C0
FC1A14 6618
FC1A16 6100028C
FC1A1A 08000007
FC1A1E 6612
FC1A20 103C0007
FC1A24 6100023A
FC1A28 3B7C000109CO
FC1A2E 426D09BE
move . 1
$466, DO
move . b
DO, D1
and . b
#7 , D1
bne
$FC1A08
move . w
#$80, (A6)
lsr . b
#3, DO
and. w
#1 , DO
lea
$9B2 ( A5) , A0
add.w
DO, A0
cmp . w
$4A6, DO
bne
$FC1 9EA
clr .w
DO
addq . b
#1 , DO
lsl.b
#1 , DO
eor .b
#7, DO
bsr
3FC1C60
move . w
$FFFF8604 , DO
btst
#6, DO
sne
(A0)
move . b
D2 , DO
bsr
$FC1C60
move . w
$9B2 (A5) , DO
or ,w
DO, $9B4 ( A5)
tst .w
$9C0 (A5)
bne
$FC1A2E
bsr
$FC1CA4
btst
#7, DO
bne
$FC1A32
move . b
#7, DO
bsr
$FC1C60
move . w
#1, $9C0 (A5)
clr . w
$9BE (A5)
_f rclock
Calculate mod 8
8th interrupt ?
Select 1772 status register
Bit 4 as drive number
wpstatus
_nf lops
Drive select bit
Write in position
Invert for active low
Select drive
dskctl, read 1772 status
Test write protect bit
and save
Restore previous status
wpstatus
Write in wplatch
deslflg, floppies already deselected?
Yes
Read 1772 status register
Motor-on bit set?
Yes, don't deselect
Both drives
Deselect
Set deslflg
Clear motoron flag
Abacus Software Atari ST Internals
FC1A32 4E7 5
rts
*************************
FC1A34 48F978F8000009E2
FC1A3C 9BCD
FC1A3E 4DF9FFFF8606
FC1A44 50F9000009BE
FC1A4A 3B4009DE
FC1A4E 3B4009E0
FC1A52 3B7C0001043E
FC1A58 2B6F00080 9CC
FC1A5E 3B6F001009C2
FC1A64 3B6F001209C6
FC1A6A 3B6F001409C4
FC1A70 3B6F001609C8
FC1A76 3B6F001809CA
FC1A7C 3B7C0002 0 9B0
FC1A82 43ED0AO6
FC1A86 4 A6D09C2
FC1A8A 6704
FC1A8C 4 3ED0A0A
FC1A90 7E00
FC1A92 3E2D09CA
FC1A96 E14F
FC1A98 E34F
FC1A9A 206D09CC
FC1A9E D1C7
FC1AA0 2B4809D0
FC1AA4 4A690000
FC1AA8 6A20
FC1AAA 61000168
FC1AAE 42690000
****************************
movem.l D3-D7 /A3-A6, $9E2
sub.l A5,A5
lea $FFFF8606, A6
st $9BE
move.w D0,$9DE(A5)
move.w D0,$9E0(A5)
move.w #1,$43E(A5)
move . 1 8 ( A7 ) , $9CC (A5)
move.w 16 ( A7 ) , $ 9C2 (A5)
move.w 18 (A7) , $9C6 (A5)
move.w 20 (A7) , $9C4 (A5)
move.w 22 (A7 ) , $9C8 (A5)
move.w 24 (A7) , $9CA (A5)
move.w #2,$9B0(A5)
lea $A06(A5),A1
tst.w $9C2(A5)
beq $FC1A90
lea $A0A(A5),A1
moveq.l #0,D7
move.w $9CA(A5),D7
lsl.w #8,D7
lsl.w #1,D7
move.l $9CC(A5),A0
add.l D7,A0
move.l AO,$9DO(A5)
tst.w (Al)
bpl $FC1ACA
bsr $FC1C14
clr.w (Al)
f loplock
Save registers
Clear A5
Address of the floppy register
Set motoron flag
deferror
currerr
flock, disable floppy VBL routine
cdma, buffer address
cdev, drive
csect, sector
ctrack, track
cside, side
ccount, number of sectors
retrycnt, 2 tries
Address dsbO
cdev, drive A?
Yes
else address dsbl
ccount, number of sectors
times 512
cdma, start DMA address
plus sector length
edma, yields end DMA address
dcurtack, current track
Valid ?
select, select drive and side
Track number to zero
Abacus Software Atari ST Internals
336
FC1AB2
610000EC
bsr
$FC1BA0
restore, find track zero
FC1AB6
6712
beq
$FC1ACA
OK ?
FC1AB8
7E0A
moveq. 1
#10, D7
Track 10
FC1ABA
6172
bsr
$FC1B2E
hseek, find track
FC1ABC
6606
bne
$FC1AC4
Error ?
FC1ABE
610000EO
bsr
$FC1BA0
restore, find track 0
FC1AC2
6706
beq
$FC1ACA
OK ?
FC1AC4
337CFFOOOOOO
move . w
#$FF00, (Al)
Track number invalid
FC1ACA
4E75
rts
***********************************.
*********************
flopfail, error in disk routine
FC1ACC
7001
moveq. 1
#1 , DO
media change to unsure
FC1ACE
61000226
bsr
$FC1CF6
set
FC1AD2
302D09E0
move . w
$9E0 (A5) ,
DO
currerr, error number
FC1AD6
4 8C0
ext . 1
DO
FC1AD8
6002
bra
$FC1ADC
********************************************************
flopok, error-free disk routine
FC1ADA
4280
clr.l
DO
Clear error number
FC1ADC
2F00
move . 1
DO,- (A7)
Save error number
FC1ADE
3CBC0086
move . w
#$86, ( A6)
Select 1772
FC1AE2
3E290000
move . w
(Al) ,D7
Get track number
FC1AE6
610001A8
bsr
$FC1C90
wdiskctl, D7 to 1772
FC1AEA
3C3C0010
move ,w
#$10, D6
Seek command
FC1AEE
610000C6
bsr
$FC1BB6
f lopcmds
FC1AF2
3039000009C2
move . w
$9C2, DO
cdev, drive number
FC1AF8
E54 8
lsl . w
#2, DO
times 4
FC1AFA
41F9000009B6
lea
$9B6, A0
acctim
FC1B00
21AD04BA0000
move . 1
$4BA(A5) ,
0 (A0, DO .w)
_hz_200 as last access time
FC1B06
0C790001000004A6
cmp . w
#1 , $4A6
nf lops
FC1B0E
6606
bne
$FC1B1 6
Only one drive?
FC1B10
216D04BA0004
move . 1
$4BA(A5) ,
4 (A0)
hz 200 as last access time
Abacus Software Atari ST Internals
FC1B16 2 0 IF
FC1B18 4CF978F8000009E2
FC1B20 427 9000004 3E
FC1B26 4E75
move . 1 (A7 ) + , DO
movem.l 59E2 , D3-D7 /A3-A6
clr.w $43E
********************************************************
FC1B28 3E39000009C4 move.w $9C4,D7
FC1B2E 33FCFFFA000009E0 move.w #-6,$9E0
FC1B36 3CBC008 6 move.w #$86, (A6)
FC1B3A 61000154
FC1B3E 3C3C0010
FC1B42 60000072
move.w $9C4,D7
move.w #-6,$9E0
move . w #$86, (A6)
bsr $FC1C90
move.w #$10, D6
bra $FC1BB6
FC1B46 33FCFFFA000009E0
FC1B4E 6150
FC1B50 664C
FC1B52 42690000
FC1B56 3CBC0082
FC1B5A 4247
FC1B5C 61000132
FC1B60 3CBC0086
FC1B64 3E3C0005
FC1B68 61000126
FC1B6C 3C3C0010
FC1B70 6144
FC1B72 662A
FC1B74 337C00050000
clr.w
#-6, $9E0
$FC1BA0
$FC1B9E
(Al)
#$82, (A6)
D7
$FC1C90
#$86, (A6)
#5, D7
$FC1C90
#$10, D6
$FC1BB6
$FC1B9E
#5, (Al)
********************************************************
FC1B7A 33FCFFFA000009EO move.w #-6,$9E0
FC1B82 3CBC0086 move.w #$86, (A6)
Error number
Restore registers
flock, release floppy VBL routine
hseek, find track
ctrack, track number
Seek error, track not found
Select 1772
wdiskctl, D7 to 1772
Seek command
f lopcmds
reseek, home and seek
Seek error, track not found
Restore
Error ?
Track number to zero
Select track register
Track zero
wdiskctl, D7 to 1772
Select data register
Track 5
wdiskctl, D7 to 1772
Seek command
f lopcmds
Error ?
Track number to 5
go2track, find track
Seek error, track not found
Select data register
Abacus Software Atari ST Internals
338
FC1B86
3E2D09C4
move . w
$9C4 ( A5) ,D7
Track number
FC1B8A
61000104
bsr
$FC1C90
wdiskctl, D7 to 1772
FC1B8E
7C14
moveq . 1
#$14, D6
Seek with verify command
FC1B90
6124
bsr
$FC1BB6
f lopcmds
FC1B92
660A
bne
$FC1B9E
Error ?
FC1B94
336D09C40000
move . w
$9C4 ( A5) , <A1)
Save track number
FC1B9A
CE3C0018
and.b
#$18, D7
Test RNF, CRC, Lost Data
FC1B9E
4E75
rts
********************************************************
restore, find track zero
FC1BA0
4246
clr.w
D6
Restore command
FC1BA2
6112
bsr
$FC1BB6
f lopcmds
FC1BA4
660E
bne
$FC1BB4
Error ?
FC1BA6
08070002
btst
#2 , D7
Test track-zero bit
FC1BAA
0A3C0004
eor .b
#4, SR
Invert Z-flag
FC1BAE
6604
bne
$FC1BB4
Not track zero?
FC1BB0
42690000
clr.w
(Al)
Track number to zero
FC1BB4
4E75
rts
********************************************************
f lopcmds
FC1BB6
30290002
move . w
2 (Al) , DO
Seek rate
FC1BBA
C03C0003
and.b
#3, DO
Bits 0 and 1
FC1BBE
8C00
or .b
DO, D6
OR with command word
FC1BC0
2E3C0004 0000
move . 1
#$40000, D7
Timeout counter
FC1BC6
3CBC0080
move . w
#$80, (A6)
Select 1772
FC1BCA
610000D8
bsr
$FC1CA4
rdiskctl
FC1BCE
08000007
btst
#7, DO
Motor on ?
FC1BD2
6606
bne
$FC1BDA
Yes
FC1BD4
2E3C00060000
move . 1
#$60000, D7
Else longer timeout
FC1BDA
610000AA
bsr
$FC1C8 6
wdiskctl6, write command in
FC1BDE
5387
subq . 1
#1 , D7
Decrement timeout counter
FC1BEO
6712
beq
$FC1BF 4
Run out?
Abacus Software Atari ST Internals
FC1BE2
0 8 3 90005FFFFF AO 1
btst
#5, 5FFFFFA01
mfp gpip, disk done?
FC1BEA
66F2
bne
5FC1BDE
No, wait
FC1BEC
610000AC
bsr
$FC1C9A
rdiskctl7 , read status
FC1BF0
4246
clr .w
D6
OK
FC1BF2
4E7 5
rts
FC1BF4
6104
bsr
$FC1BFA
Reset 1772
FC1BF6
7C01
moveq .
.1 #1 , D6
Error
FC1BF8
4E7 5
rts
ini i i a3 ;
u>
GO
VO
FC1C14
426D09C0
clr .w
$9C0 (A5)
FC1C18
302D09C2
move . w
$9C2 (A5) , DO
FC1C1C
5200
addq . b
#1 , DO
FC1C1E
E308
lsl.b
#1, DO
FC1C20
806D09C8
or .w
$9C8 (A5) , DO
FC1C24
0A000007
eor .b
#7, DO
FC1C28
C03C0007
and.b
#7, DO
FC1C2C
6132
bsr
$FC1C60
FC1C2E
3CBC0082
move . w
#$82, (A6)
FC1C32
3E290000
move .w
(Al) ,D7
FC1C36
6158
bsr
$FC1C90
FC1C38
422D09DA
clr .b
$9DA(A5)
***************************
********
XXXXXXXXXJl * ‘
FC1BFA
3CBC0080
move . w
#$80, (A6) -
FC1BFE
3E3C00D0
move . w
#$D0,D7
FC1C02
6100008C
bsr
$FC1C90
FC1C06
3E3COOOF
move . w
#$F , D7
FC1C0A
51CFFFFE
dbra
D7 , $FC1C0A
FC1C0E
6100008A
bsr
$FC1C9A
FC1C12
4E75
rts
Reset 1772, Reset Floppy Controller
Select command register
Reset command
wdiskctl, D7 to 1772
Delay counter
Time run out?
rdiskctl, read status
select, select drive and side
Clear deslflg
cdev, drive number
Calculate bit number
csid, side in bit 0
Invert bits for active low
setporta, set bits
Select track register
Get track number
wdiskctl, D7 to 1772
tmpdma, clear bits 24-31
Abacus Software Atari ST Internals
FC1C3C
3CBC0084
move . w
#$84, (A6)
FC1C40
3E2D09C6
move . w
$9C6 (A5) , D7
FC1C44
61 4 A
bsr
$FC1C90
FC1C46
13ED09CFFFFF860D
move . b
$ 9CF (A5) , $FFFF860D
FC1C4E
13ED09CEFFFF860B
move . b
$ 9CE ( A5) , $FFFF860B
FC1C56
13ED09CDFFFF8609
move . b
$ 9CD ( A5) , $FFFF8609
FC1C5E
4E75
rts
.*****************************************************,
r C1C60
40E7
move . w
SR, -(AT)
FC1C62
007C0700
or .w
#$700, SR
FC1C66
13FCOO0EFFFF8800
move . b
#$E, $FFFF8800
FC1C6E
1239FFFF8800
move . b
$FFFF8800,D1
FC1C74
1401
move . b
D1,D2
FC1C76
C23C00F8
and.b
#$F8,D1
FC1C7A
8200
or ,b
DO, D1
FC1C7C
13C1FFFF8802
move . b
Dl, $FFFF8802
FC1C82
4 6DF
move . w
(A7 ) +, SR
FC1C84
4E75
rts
********************************************************
FC1C86 6124 bsr $FC1CAC
FC1C88 33C6FFFF8604 move.w D6,$FFFF8604
FC1C8E 601C bra $FC1CAC
********************************************************
FC1C90 61 1A bsr $FC1CAC
FC1C92 33C7FFFF8604 move.w D7,$FFFF8604
FC1C98 6012 bra $FC1CAC
Select sector register
csect, get sector number
wdiskctl, D7 to 1772
Set DMA address
setporta, select drive and side
Save status
IPL 7, no interrupts
Select port A
Read data from port
and save
Clear bits 0-2
Set new bits
Write result in port A
Reset status
wdiskct 6
Delay loop for disk controller
D6 to disk controller
Delay loop for disk controller
wdiskctl
Delay loop for disk controller
D7 to disk controller
Delay loop for disk controller
Abacus Software Atari ST Internals
u>
FC1C9A
6110
bsr
$FC1CAC
FC1C9C
3E3 9FFFF8 604
move . w
SFFFF8 604 , D7
FC1CA2
6008
bra
SFC1CAC
************************************
■*************’
FC1CA4
6106
bsr
$FC1CAC
FC1CA6
3039FFFF8604
move . w
$FFFF8604 , DO
rC 1CAC
4 0E7
move . w
SR, - ( A7 )
rCICAE
3F07
move . w
D7,-(A7)
FC1CB0
3E3C0020
move . w
#$20, D7
FC1CB4
51CFFFFE
dbra
D7 , $FC1CB4
FC1CB8
3E1F
move . w
(A7 ) +,D7
FC1CBA
4 6DF
move . w
(A7) + , SR
FC1CBC
4E75
rts
*************************************************
FC1CBE
OC790001000004A6
cmp. w
#1 , $4A6
FC1CC6
662C
bne
$FC1CF4
FC1CC8
302F0010
move . w
16 (A7 ) , DO
FC1CCC
B07 900005 622
cmp. w
$5622, DO
FC1CD2
67 1C
beq
$FC1CF0
FC1CD4
3F00
move . w
DO, - (A7)
FC1CD6
3F3CFFEF
move . w
#-17, -(A7)
FC1CDA
6100EA62
bsr
$FC073E
FC1CDE
584F
addq . w
#4 , A7
FC1CE0
33FCFFFF000009B4
move . w
#-l,$9B4
FC1CE8
33 EF 001000005622
move . w
16(A7) ,$5622
FC1CF0
42 6F0010
clr .w
16 ( A7 )
FC1CF4
4E75
rts
rdiskct7
Delay loop for disk controller
Disk controller status to D7
Delay loop for disk controller
rdiskctl
Delay loop for disk controller
Disk controller status to DO
Save status
Save D7
Counter
Delay loop
D7 back
Status back
change, test for disk change
_nf lops
0 or 2 drives, done
Drive number
Same disk number?
Yes
Drive number
'Insert Disk'
Critical error handler
Correct stack pointer
wplatch, status unsure
Save disk number
Drive number to zero
Abacus Software Atari ST Internals
342
*^******-k****ic*-k****-k-k***-k***-k-k-k**-k-k-kickic***-k***ir-k-kicic-k*:*ir
FC1CF6 41F900004DB8 lea $4DB8,AO
FC1CFC 1F00 move.b D0,-(A7)
FC1CFE 302D09C2 move . w $9C2{A5),D0
FC1D02 119F0000 move.b (A7 ) +, 0 (AO, DO . w)
FC1D06 4E75 rts
FC1D08 AE
FC1D09 D6
FC1D0A 8C
FC1D0B 17
FC1D0C FB
FC1D0D 80
FC1D0E 6A
FC1D0F 2B
FC1D10 A6
FC1D11 00
dc.b $AE
dc.b $D6
dc.b $8C
dc.b $17
dc.b $FB
dc.b $80
dc.b $6A
dc.b $2B
dc.b $A6
dc.b $00
FC1D12 4BF900000000
FC1D18 4 1ED0E01
FC1D1C 610000DE
FC1D20 04000050
FC1D24 1400
FC1D26 E982
FC1D28 610000D2
FC1D2C D400
FC1D2E EB82
lea $0,A5
lea $E01(A5),A0
bsr $FC1DFC
sub.b #80, DO
move.b D0,D2
asl.l #4 , D2
bsr $FC1DFC
add.b DO, D2
asl.l #5, D2
setdmode, set Drive Change Mode
Address of the bpb
Save mode
cdev, get drive number
Set drive mode
dskf, disk flags
Jdostime, IKBD format to DOS format
Clear A5
Pointer to clock-time buffer
bcdbin
Subtract offset of 80
Year
Write in position
bcdbin
Add month
Write in position
Abacus Software Atari ST Internals
FC1D30 610000CA
FC1D34 D400
FC1D36 EB82
FC1D38 610000C2
FC1D3C D400
FC1D3E ED82
FC1D40 610000BA
FC1D44 D400
FC1D46 EB82
FC1D48 610000B2
FC1D4C E208
FC1D4E D400
FC1D50 2B420E0A
FC1D54 1B7C00000E4C
FC1D5A 4E75
bsr $FC1DFC
add.b DO , D2
asl.l #5, D2
bsr $FC1DFC
add.b DO , D2
asl.l #6, D2
bsr $FC1DFC
add.b DO , D2
asl.l #5 , D2
bsr $FC1DFC
lsr.b #1,D0
add.b DO, D2
move.l D2,$E0A(A5)
move.b #0,$E4C(A5)
rts
U>
U>
FC1D5C
1B7CFFFF0E4C
move . b
#-l,$E4C(A5)
FC1D62
123C001C
move.b
#$1C,D1
FC1D66
61000240
bsr
$FC1FA8
FC1D6A
4A2D0E4C
tst .b
$E4C ( A5)
FC1D6E
66FA
bne
$FC1D6A
FC1D70
202D0E0A
move . 1
$E0A(A5) , DO
FC1D74
4E75
rts
********************************************************
FC1D76 2B6F00040E0E move.l 4 ( A7 ) , $EOE ( A5)
********************************************************
FC1D7C 4 1F900000E1 8 lea $E18,A0
bcdbin
Add day
Write in position
bcdbin
Add hour
Write in position
bcdbin
Add minute
Write in position
bcdbin
2-second resolution
Add seconds
Save new time
Clear handshake flag
gettime, get current time and date
Set handshake flag
Get time of day command
Send to IKBD
New time arrived?
No, wait
Put time in DO
settime, set time and data
Pass time
ikbdtime
Pointer to end of time buffer
Abacus Software Atari ST Internals
344
FC1D82
242D0E0E
move . 1
$E0E ( A5) , D2
Get time to convert
FC1D86
1002
move . b
D2 , DO
in DO
FC1D88
02 00001F
and.b
#$1F, DO
Bits 0-4, seconds
FC1D8C
E300
asl.b
#1 , DO
2-second resolution
FC1D8E
6154
bsr
$FC1DE4
convert
FC1D90
EA8A
lsr.l
#5 , D2
Minutes
FC1D92
1002
move . b
D2 , DO
FC1D94
0200003F
and.b
#$3F, DO
Bits 0-5
FC1D98
614A
bsr
$FC1DE4
convert
FC1D9A
EC8A
lsr.l
#6, D2
Hours
FC1D9C
1002
move . b
D2 , DO
FC1D9E
02 00001F
and.b
#$1F, DO
Bits 0-4
FC1DA2
6140
bsr
5FC1DE4
convert
FC1DA4
EA8A
lsr.l
#5, D2
Day
FC1DA6
1002
move . b
o
Q
csi
Q
FC1DA8
0200001F
and.b
#$1F, DO
Bits 0-4
FC1DAC
6136
bsr
$FC1DE4
convert
FC1DAE
EA8A
lsr.l
#5, D2
Month
FC1DB0
1002
move . b
D2 , DO
FC1DB2
0200000F
and.b
#$F, DO
Bits 0-3
FC1DB6
612C
bsr
$FC1DE4
convert
FC1DB8
E88A
lsr.l
#4 , D2
Year
FC1DBA
1002
move . b
D2 , DO
FC1DBC
0200007F
and.b
#$7F , DO
Bits 0-6
FC1DC0
6122
bsr
$FC1DE4
convert
FC1DC2
06100080
add.b
#$80, (A0)
Add offset
FC1DC6
123C001B
move . b
#$1B, D1
Set time of day command
FC1DCA
610001DC
bsr
$FC1FA8
Send to IKBD
Abacus Software Atari ST Internals
345
FC1DCE
7605
moveq . 1
#5 , D3
FC1DD0
45F900000E12
lea
$E12 , A2
FC1DD6
610001F0
bsr
5FC1FC8
FC1DDA
123C001C
move .b
#$1C, D1
FC1DDE
610001C8
bsr
$FC1FA8
FC1DE2
4E75
rts
***********************************
**********
FC1DE4
7200
moveq . 1
#0 , D1
i C1DE6
7 60A
moveq. 1
#10, D3
FC1DE8
9003
sub.b
D3, DO
FC1DEA
6B04
bmi
$FC1DF0
FC1DEC
5201
addq . b
#1, D1
FC1DEE
60F8
bra
$FC1DE8
FC1DF0
0600000A
add.b
#10, DO
FC1DF4
E901
asl.b
#4 , D1
FC1DF6
D001
add.b
Dl, DO
FC1DF8
1100
move . b
DO, -(A0)
FC1DFA
4E75
rts
FC1DFC
7000
moveq. 1
#0, DO
FC1DFE
1010
move . b
(A0) , DO
FC1E00
E808
lsr .b
o
Q
FC1E02
E308
lsl.b
#1 , DO
FC1E04
1200
move . b
DO , Dl
FC1E06
E500
asl.b
#2, DO
FC1E08
D001
add.b
o
o
o
FC1E0A
1218
move . b
(A0) +, Dl
Number of bytes minus 1
Address of the string
ikbdws, send string
Get time of day command
Send to IKBD
binbcd, convert byte to BCD
Ten's counter
Subtract 10
Increment ten's counter
Generate one's place
Tens in upper nibble
plus ones
Write in buffer
bcdbin, convert BCD to binary
BCD byte
Tens place
times 2
times 4
One's place
Abacus Software Atari ST Internals
346
FC1E0C 0241000F
FC1E10 DO 4 1
FC1E12 4E75
and.w #$F,D1
add.w D1,D0
rts
isolate
and add
FC1E14 7 OFF
FC1E16 1439FFFFFC04
FC1E1C 08020001
FC1E20 6602
FC1E22 7000
FC1E24 4E75
moveq.l #-l , DO
move.b $FFFFFC04,D2
btst #1,D2
bne $FC1E24
moveq.l #0,D0
rts
midiost, MIDI output status
Default to OK
Read MIDI ACIA status
and test
OK
Not OK, ACIA is sending
FC1E26
322F0006
move .w
6(A7) ,D1
FC1E2A
43F9FFFFFC04
lea
$FFFFFC04,A1
FC1E30
14290000
move . b
(Al) ,D2
FC1E34
08020001
btst
#1 , D2
FC1E38
67F6
beq
$FC1E30
FC1E3A
13410002
move . b
D1 , 2 (Al)
FC1E3E
4E75
rts
midiwc, output character to MIDI
Get character
MIDI ACIA control
Get MIDI status
OK ?
No, wait
Output byte
FC1E40 7600
FC1E42 3 62F0004
FC1E46 24 6F0006
FC1E4A 12 1A
FC1E4C 61DC
moveq.l #0,D3
move .w 4 (A7) , D3
move. 1 6 (A7) , A2
move .b (A2) +, D1
bsr $FC1E2A
FC1E4E 51CBFFFA dbra D3,$FC1E4A
FC1E52 4E75 rts
midiws, send string to MIDI
(unnecessary ! )
Length of the string - 1
Address of the string
Get byte
and send
Next byte
Abacus Software Atari ST Internals
oo
"4
********************************************************
midstat, MIDI receiver status
FC1E54
4 1ED0DBE
lea
$DBE(A5) , AO
iorec for MIDI
FC1E58
43F9FFFFFC04
lea
$FFFFFCG 4 , A1
MIDI ACIA control
FC1E5E
7 OFF
moveq . 1
=#=
1
h-1
D
o
Default to OK
FC1E60
45E80006
lea
6 (A0) ,A2
Head index
FC1E64
47E80008
lea
8 (A0) , A3
Tail index
FC1E68
B54B
cmpm . w
(A3 ) +, (A2) +
Characters in buffer?
FC1E6A
6602
bne
$FC1E6E
Yes
FC1E6C
7000
moveq . 1
o
Q
o
Character ready
FC1E6E
4E75
rts
********************************************************
midin, get character from MIDI
FC1E70
61E2
bsr
5FC1E54
midstat, character ready?
FC1E72
4A4 0
tst . w
DO
FC1E74
67FA
beq
$FC1E70
No, wait
FC1E76
40E7
move . w
SR, - (A7 )
Save status
FC1E78
007C0700
or .w
#$700, SR
IPL 7, disable interrupts
FC1E7C
32280006
move . w
6 (A0) ,D1
Head index
FC1E80
B2 680008
cmp.w
8 (A0) ,D1
Compare with tail index
FC1E84
6716
beq
$FC1E9C
Buffer empty
FC1E86
5241
addq . w
#1, D1
Increment head index
FC1E88
B2680004
cmp.w
4 (A0) ,D1
Larger buffer size?
FC1E8C
6502
bcs
$FC1E90
No
FC1E8E
7200
moveq. 1
#0 , D1
Start again beginning of buffer
FC1E90
22680000
move . 1
(A0) , A1
Buffer address
FC1E94
10311000
move . b
0 (Al, Dl.w) , DO
Get character from buffer
FC1E98
31410006
move . w
Dl, 6 (AO)
Save new head index
FC1E9C
4 6DF
move . w
(A7 ) +, SR
Get status
FC1E9E
4E75
rts
Abacus Software Atari ST Internals
FC1EA0 082D00040E4A
FC1EA6 660000DE
FC1EAA 242D04BA
FC1EAE 94AD0E3E
FC1EB2 OC82000003E8
FC1EB8 6518
FC1EBA 242D04BA
FC1EBE 6174
FC1EC0 4A40
FC1EC2 6618
FC1EC4 262D04BA
FC1EC8 9682
FC1ECA OC8300001770
FC1EDO 6DEC
FC1ED2 7000
£ FC1ED4 2B6DO4BA0E3E
fJ° FC1EDA 4E75
btst #4 , $E4A ( A5 )
bne $FC1F86
move . 1 $4 BA ( A5) , D2
sub. 1 $E3E(A5),D2
cmp.l #1000, D2
bcs 5FC1ED2
move.l $4BA(A5),D2
bsr $FC1F34
tst.w DO
bne $FC1EDC
move.l $4BA(A5),D3
sub. 1 D2,D3
cmp.l #6000, D3
bit $FC1EBE
moveq.l #0, DO
move.l $4BA(A5) ,$E3E(A5)
rts
FC1EDC
40C3
move . w
SR, D3
FC1EDE
007C0700
or .w
#$700, SR
FC1EE2
7207
moveq. 1
#7, D1
FC1EE4
61000E6E
bsr
$FC2D54
FC1EE8
00000080
or .b
#$80, DO
FC1EEC
7287
moveq. 1
#$87, D1
FC1EEE
61000E64
bsr
$FC2D54
FC1EF2
4 6C3
move . w
D3, SR
FC1EF4
302F0006
move . w
6 (A7 ) , DO
FC1EF8
728F
moveq . 1
#$8F,D1
lstout, printer output
RS 232 printer?
Yes, output to RS 232
_hz_200, 200 Hz counter
minus last time
Less than 10 seconds
Yes
_hz_200
lstostat, printer ready?
Yes, output character
_hz_200, 200 Hz counter
minus last time
More than 30 seconds?
No, wait
Character not sent
Save hz 200 as new time
Output character to parallel port
Save status
IPL 7, no interrupts
Register 7
select
Port B
Write register 7
Port B to output
Save status
Character to output
Write port B
Abacus Software Atari ST Internals
FC1EFA 61000E58
FC1EFE 610E
FC1F00 610C
FC1F02 6104
FC1F04 70FF
FC1F06 4E75
bsr $FC2D54
bsr $FC1F0E
bsr $FC1F0E
bsr $FC1F08
moveq.l #-l,D0
rts
********************************************************
FC1F08 7420 moveq.l #$20, D2
FC1F0A 60000E8A bra $FC2D96
********************************************************
FC1F0E 74DF moveq.l #$DF,D2
FC1F10 60000EAA bra $FC2DBC
Lb
VO
FC1F14
7207
moveq. 1
#7 , D1
FC1F16
61000E3C
bsr
5FC2D54
FC1F1A
0200007F
and.b
#$7F, DO
FC1F1E
7287
moveq . 1
#$87, D1
FC1F20
61000E32
bsr
$FC2D54
FC1F24
61E2
bsr
$FC1F08
FC1F26
610C
bsr
$FC1F34
FC1F28
4A40
tst . w
DO
FC1F2A
66FA
bne
$FC1F2 6
FC1F2C
61E0
bsr
$FC1F0E
Output character
Strobe low
Strobe low
Strobe high
OK
Strobe high
Bit 5
set in port A
Strobe low
Bit 5
clear in port A
lstin, get character from parallel port
Mixer
Select register in PSG
Port B to input
Write register 7
giacces
Strobe high = receiver ready
lstostat, character arrived?
No, wait
Strobe low = receiver busy
Abacus Software Atari ST Internals
350
FC1F2E
7 2 OF
moveq . 1
#15, D1
Select port B
FC1F30
60000E22
bra
$FC2D54
Read byte from port
********************************************************
lstostat, printer output stat
FC1F34
41F9FFFFFA01
lea
$FFFFFA01, AO
mfp gpip
FC1F3A
7 OFF
moveq. 1
#-l , DO
Default to ok
FC1F3C
082800000000
btst
#0, (A0)
Busy to low ?
FC1F42
6702
beq
$FC1F4 6
Yes
FC1F44
7000
moveq. 1
#0, DO
Printer not ready
FC1F46
4E75
rts
********************************************************
auxistat, RS 232 input status
FC1F48
4 1ED0D8E
lea
$D8E(A5) , A0
iorec for rs232
FC1F4C
70FF
moveq . 1
#-l , DO
Default to OK
FC1F4E
45E80006
lea
6 (A0) ,A2
Head index
FC1F52
4 7E80008
lea
8 (A0) , A3
Tail index
FC1F56
B54B
cmpm . w
(A3) +, (A2 ) +
Buffer empty?
FC1F58
6602
bne
$FC1F5C
No
FC1F5A
7000
moveq . 1
#0, DO
No characters ready
FC1F5C
4E75
rts
********************************************************
auxin, RS 232 input
FC1F5E
61E8
bsr
$FC1F4 8
auxistat, character ready?
FC1F60
4A40
tst . w
DO
FC1F62
67FA
beq
$FC1F5E
No, wait
FC1F64
610005D6
bsr
$FC253C
rs232get, get character
Abacus Software Atari ST Internals
FC1F68 024000FF
FC1F6C 4E75
and. w #$FF , DO
rts
Isolate bits 0-7
auxostat, RS 232 output status
iorec for RS 232
Default to OK
Tail index
Test for wrap around
Compare with head index
OK
No space in buffer
auxout, RS 232 output
Get byte
rs232put, write in buffer
Not sent, try again
ikbdost, IKBD output status
Default to ok
Keyboard ACIA status
ACIA ready ?
Yes
Not used
ikbdwc, send byte to IKBD
Get byte
Keyboard ACIA control
Get ACIA status
Ready?
Abacus Software Atari ST Internals
352
FC1FB6 67F6 beq $FC1FAE No, wait
FC1FB8 13410002 move.b D1,2(A1) Send byte
FC1FBC 4E75 rts
********************************************************
FC1FBE 7600 moveq.l #0,D3
FC1FC0 362F0004 move . w 4{A7),D3
FC1FC4 24 6F0006 move . 1 6(A7),A2
FC1FC8 121A move.b (A2)+,D1
FC1FCA 61DC bsr $FC1FA8
FC1FCC 51CBFFFA dbra D3,$FC1FC8
FC1FD0 4E75 rts
********************************************************
FC1FD2 4 1EDODB0 lea $DB0(A5),A0
FC1FD6 70FF moveq.l #-l,D0
FC1FD8 45E80006 lea 6(A0),A2
FC1FDC 47E80008 lea 8 (A0), A3
FC1FE0 B54B cmpm.w (A3)+,(A2)+
FC1FE2 6602 bne 5FC1FE6
FC1FE4 7000 moveq.l #0,DO
FC1FE6 4E75 rts
*****************
***************************************
conin, get character from keyboard
FC1FE8
61E8
bsr
$FC1FD2
constat, key pressed?
FC1FEA
4A4 0
tst . w
DO
FC1FEC
67FA
beq
$FC1FE8
No, wait
FC1FEE
4 0E7
move . w
SR, - ( A7 )
Save status
FC1FF0
007C0700
or . w
#$700, SR
IPL 7, disable interrupts
FC1FF4
32280006
move . w
6 (A0) ,D1
Head index
FC1FF8
B2680008
cmp . w
8 (A0) ,D1
Compare with tail index
FC1FFC
6716
beq
$FC2014
Buffer empty?
constat, keybaord input status
iorec for keyboard
Default for OK
Head index
Tail index
Buffer empty?
No, OK
No characters there
ikbdws, send string to keyboard
unnecessary !
Number of characters minus 1
Address of the string
Get byte
Send to keyboard
Next byte
Abacus Software Atari ST Internals
u>
u>
FC1FFE
5841
addq . w
#4 , D1
Increment head index
FC2000
B2680004
cmp . w
4 (A0) ,D1
Greater or equal to buffer
size
FC2004
6502
bcs
$FC2 008
No
FC2006
7200
moveq . 1
#0 , D1
Buffer point back to start
FC2008
22680000
move . 1
(A0) , A1
Buffer address
FC200C
20311000
move . 1
0 ( A1 , D1 . w) , DO
Get character
FC2010
31410006
move . w
Dl, 6 (A0)
Save new head index
FC2014
4 6DF
move . w
(A7) +, SR
Get status
FC2016
4E75
rts
********************************************************
conoutst, console output statu:
FC2018
7 OFF
moveq . 1
#-l, DO
Status always OK
FC201A
4E7 5
rts
********************************************************
ringbel, tone after CTRL G
FC201C
082D00020484
btst
#2, $484 (A5)
conterm, sound enabled ?
FC2022
67 0E
beq
$FC2032
No
FC2024
2B7C00FC307 60E4 4
move . 1
#$FC3076, $E4 4 (A5)
Pointer to sound table for
ell
FC202C
1B7COOOOOE4 8
move . b
#0, $E48 (A5)
Start sound timer
FC2032
4E75
rts
********************************************************
Keyboard table, unshifted
FC2034
001 B3 13233343536
dc.b
$00, esc, '1', '2', ’3',
'4
', '5', '6'
FC203C
37383 93 09E270809
dc .b
'7', '8', '9', '0*, 'O',
' '
',bs, tab
FC2044
7177 6572747A7 569
dc.b
'q', 'w', 'e', 'r', 't'.
' z
', 'u', 'i'
FC204C
6F70812B0D006173
dc.b
'o', 'p', 'A', '+ ' , cr.
$00, 'a' , 's'
FC2054
64666768 6A6B6C 94
dc.b
'd', 'f', >g', 'h’, ’ j ' ,
1 k
', '1', '!'
FC205C
8423007E79786376
dc.b
'ft' , '#',$00, 'y'.
1 X
' , 'c ' , ' v'
FC2064
62 6E6D2C2E2D0000
dc.b
'b', 'n', 'm' ,
* _
',$00, $00
FC206C
0020000000000000
dc.b
$00,' ',$00, $00, $00,
$00, $00, $00
FC2074
0000000000000000
dc.b
$00, $00, $00, $00, $00,
$00, $00, $00
FC207C
00002D0000002B00
dc.b
$00, $00, '-',$00, $00,
$00, '+',$00
Abacus Software Atari ST Internals
354
FC2084 00OO0O7FOOO00OQO dc.b $00, $00, $00, del, $00, $00, $00, $00
FC208C 0000000000000000 dc.b $00, $00, $00, $00, $00, $00, $00, $00
FC2094 3C00002 82 92F2A37 dc.b ' < ' , $00, $00, ' ( 1 , ' ) ' , ' / ' , ' * ' , ' 7 1
FC209C 3839343536313233 dc.b ' 8 ' , ' 9 ' , ' 4 ' , 1 5 ' , ' 6 ' , ' 1 ' , ' 2 ' , ' 3 '
FC20A4 302EODOOOOOOOOOO dc.b '0','.',cr, $00, $00, $00, $00, $00
FC20AC 0000000000000000 dc.b $00, $00, $00, $00, $00, $00, $00, $00
******************************************************** Keyboard table, shifted
FC20B4
001B2122DD242526
dc.b
$00, esc.
1 t 1
t
Mil I x 1
t ' r
'$',
FC20BC
2F28293D3F600809
dc.b
')
l — l l *) l
t - r
' ‘ ' ,bs, tab
FC20C4
5157 4552 545A554 9
dc.b
'Q', 'W\
•E',
'R', 'T',
'Z', 'O', 'I'
FC20CC
4F509A2A0D004153
dc.b
'O' , 'P' ,
'6' ,
' * ' , cr ,
$00, 'A' , 'S'
FC20D4
444647484A4B4C99
dc.b
'D' , 'F' ,
■G',
'H', 'J',
'K' , ' L ' , 'o'
FC20DC
8E5E007C59584356
dc.b
1 A 1 1^1
e t t
$00,
' | ', 'Y',
'X', 'C\ 'V'
FC20E4
424E4D3B3A5F0000
dc.b
'B', 'N',
'M' ,
i . * t . t
t t • r
, $00, $00
FC20EC
0020000000000000
dc.b
$00,' ',
$00,
$00, $00,
$00, $00, $00
FC20F4
0000000000000037
dc.b
$00, $00,
$00,
$00, $00,
$00, $00, '7 '
FC20FC
38002D3400362B00
dc.b
'8', $00,
1 — 1
r
'4', $00,
'6', '+',$00
FC2104
3200307F00000000
dc.b
'2', $00,
'O',
del, $00,
$00, $00, $00
FC210C
0000000000000000
dc.b
$00, $00,
$00,
$00, $00,
$00, $00, $00
FC2114
3E000028292F2A37
dc.b
■>',$00,
$00,
'7'
FC211C
3839343536313233
dc.b
'8', '9',
'4',
■5', '6',
'1', '2', '3'
FC2124
302EODOOOOOOOOOO
dc.b
1 n I ' '
cr.
$00, $00,
$00, $00, $00
FC212C
0000000000000000
dc.b
$00, $00,
$00,
$00, $00,
$00, $00, $00
FC2134
001B313233343536
dc.b
$00,
esc
1 1 1 1
■ t J- r
'2',
•3',
'4',
■5', '6'
FC213C
373839309E270809
dc.b
'7',
'8'
, '9',
'O',
'u'.
III
f
bs, tab
FC2144
515 7 4552 54 5A554 9
dc.b
'Q',
'W'
, 'E',
'R',
'T\
'Z',
'O', 'I'
FC214C
4F50 9A2B0D004 153
dc.b
'O',
'P'
,'o'r
cr.
$00,
'A' , 'S'
FC2154
444647484A4B4C99
dc.b
'D',
'F'
, 'G\
'H',
' J',
■K',
'L' , 'o'
FC215C
8E23007E59584356
dc.b
'e' ,
'#'
,$00,
1 ~ *
t
'Y',
'X',
'C' , 'V'
FC2164
424E4D2C2E2D0000
dc.b
'B',
■N'
, 'M',
t 1
f r
I I
• f
1 _ 1
r
$00, $00
FC216C
0020000000000000
dc.b
$00,
1 1
,$00,
$00,
$00,
$00,
$00, $00
Abacus Software Atari ST Internals
355
FC2174
0000000000000000
dc .b
$00, $00, $00, $00
FC217C
00002D0000002BOO
dc .b
$00, $00, , $00
FC2184
OOOOOO7FOOOOOOOO
dc .b
$00, $00, $00, del
FC218C
0000000000000000
dc .b
$00, $00, $00, $00
FC2194
3C000028292F2A37
dc .b
'<' , $00, $00, ' ( 1
FC219C
3839343536313233
dc .b
'8', '9', '4', '5'
FC21A4
302EODOOOOOOOOOO
dc .b
'O' , ' . ', $00, $00
FC21AC
0000000000000000
dc .b
$00, $00, $00, $00
**************************
*************************
FC21B4
41F9FFFFFA01
lea
$FFFFFA01 , A0
FC21BA
7000
moveq . 1
#0, DO
FC21BC
01C80000
movep . 1
DO, 0 (A0)
FC21C0
01C80008
movep . 1
DO, 8 (A0)
FC21C4
01C80010
movep. 1
DO, 16 (A0)
FC21C8
117C00480016
move . b
#$48, 22 (A0)
FC21CE
3B7C11110E42
move . w
#$1111, $E42 (A5)
FC21D4
3B7C00140442
move . w
#$14, $442 (A5)
FC21DA
7002
moveq . 1
#2, DO
FC21DC
7250
moveq. 1
#80, D1
FC21DE
343C00C0
move . w
#$C0,D2
FC21E2
61000182
bsr
$FC2366
FC21E6
45F900FC2F7 8
lea
$FC2F78, A2
FC21EC
7005
moveq . 1
#5, DO
FC21EE
6100022C
bsr
$FC241C
FC21F2
7003
moveq . 1
#3, DO
FC21F4
7201
moveq . 1
#1, D1
FC21F6
7402
moveq . 1
#2 , D2
FC21F8
6100016C
bsr
$FC2366
FC21FC
203C00980101
move . 1
#$980101, DO
FC2202
01C80026
movep . 1
DO, $26 (A0)
FC2206
61000B84
bsr
$FC2D8C
, $00, $00, $00, $00
, $00, $00, ' + ' , $00
, $00, $00, $00, $00
, $00, $00, $00, $00
,'6', ' 1 ' , '2 ' ,'3'
, $00, $00, $00, $00
,$00, $00, $00, $00
**** initmfp, initialize MFP 68901
Address of mfp
Initialize register with zero
gpip to iera
ierb to isra
isrb to vr
MFP non-autovector number to $40, set S-bit
Timer C bit map to every 4th IRQ
_timer_ms to 20 ms
Select timer C
/ 64 for 200 Hz
192
Initialize timer and interrupt vector
Timer C interrupt routine
Timer C interrupt number
initint, initialize interrupt
Select timer D
/4 for 9600 baud
9600 baud
Initialize timer and interrupt vector
$00, $98, $01, $01
to scr, ucr, rsr, tsr
DTR on
Abacus Software Atari ST Internals
356
FC220A 61000B7 8
FC220E 4 1ED0D8E
FC2212 43F900FC2334
FC2218 7021
FC221A 610000F0
FC221E 4 1ED0DBE
FC2222 43F900FC2326
FC2228 700D
FC222A 610000E0
FC222E 203C00FC288E
FC2234 2B400DD0
FC2238 2B400DD4
FC223C 2B7C00FC2CE20DCC
FC2244 2B7COOFC284AODE8
FC224C 2B7C00FC285A0DEC
FC2254 13FC0003FFFFFC04
FC225C 13FC0095FFFFFC04
FC2264 1B7C00070484
FC226A 2B7C00FC1D120DE0
FC2272 203C00FC230A
FC2278 2B400DD8
FC227C 2B400DDC
FC2280 2B400DE4
FC2284 7000
FC2286 2B400E44
FC228A 1B400E48
FC228E 1B400E4 9
FC2292 2B400E3E
FC2296 6100FC70
FC229A 1B7C000F0E3C
FC22A0 1B7C00020E3D
FC22A6 4 1ED0DB0
bsr
5FC2D84
lea
$D8E ( A5) , AO
lea
5FC2334, A1
moveq . 1
#33, DO
bsr
$FC230C
lea
$DBE (A5) , AO
lea
$FC232 6, A1
moveq . 1
#13, DO
bsr
$FC230C
move . 1
#$FC288E, DO
move . 1
DO, $DD0 (A5)
move . 1
DO, $DD4 (A5 )
move . 1
#$FC2CE2,$DCC(A5)
move . 1
#$FC284A, $DE8(A5)
move . 1
#$FC285A,$DEC(A5)
move . b
#3, $FFFFFC04
move . b
#$95,$FFFFFC04
move . b
#7, $484 (AS)
move . 1
#$FC1D12,$DE0(A5)
move . 1
#$FC230A, DO
move . 1
DO, $DD8 (A5 )
move . 1
DO, $DDC(A5)
move . 1
DO, $DE4 (A5 )
moveq . 1
#0, DO
move . 1
DO, $E44 { A5 )
move . b
DO, $E48 (A5)
move . b
DO, $E4 9 (A5 )
move . 1
DO, $E3E (A5)
bsr
$FC1F08
move . b
#$F,$E3C(A5)
move . b
#2 , $E3D ( A5 )
lea
$DB0 ( A5) , A0
RTS on
Pointer to iorec for RS 232
Start data for iorec
34 bytes
Copy to RAM
Pointer to iorec for MIDI
Start data for iorec
14 bytes
Copy to RAM
Keyboard and MIDI error vector
Pointer to keyboard error routine
Pointer to MIDI error routine
sysmidi vector
midisys vector
ikbdsys vector
MIDI ACIA control, master reset
/16, 8 Bit, 1 stop bit, no parity
conterm, keyclick, repeat und bell enable
Jdostime, time vector
Pointer to rts
statvec, IKBD status package
mousevec, mouse action
joyvec, joystick action
Clear sound variables
Sound pointer
Delay timer
Temp value
Printer timeout
Strobe to high
Keyboard delay 1
Keyboard delay 2
Pointer to iorec keyboard
Abacus Software Atari ST Internals
357
FC22AA 4 3F900FC2 3 1 8
FC22B0 7 OOD
FC22B2 6158
FC22B4 61000C58
FC22B8 13FC0OO3FFFFFCOO
FC22C0 13FC0096FFFFFC00
FC22C8 267C00FC2356
FC22CE 7203
FC22D0 2401
FC22D2 2001
FC22D4 06000009
FC22D8 E582
FC22DA 24732000
FC22DE 6100013C
FC22E2 51C9FFEC
FC22E6 45F900FC281C
FC22EC 7006
FC22EE 6100012C
FC22F2 45F900FC26B2
FC22F8 7002
FC22FA 61000120
FC22FE 247C00FC2314
FC2304 7603
FC2306 6100FCC0
FC230A 4E75
FC230C 10D9
FC230E 51C8FFFC
FC2312 4E75
lea $FC2 31 8 , A1
moveq.l #13, DO
bsr $FC2 30C
bsr $FC2F0E
move . b #3,$FFFFFC00
move.b #$96, 5FFFFFC00
move . 1 #$FC2356,A3
moveq.l #3,D1
move . 1 D1,D2
move.l D1,D0
add.b #9, DO
asl.l #2 , D2
move.l 0(A3,D2.w) ,A2
bsr $FC2 4 1C
dbra D1,$FC22D0
lea $FC2 81C, A2
moveq.l #6, DO
bsr $FC2 4 1C
lea $FC2 6B2 , A2
moveq.l #2, DO
bsr $FC2 4 1C
move.l #$FC2314,A2
moveq.l #3,D3
bsr $FC1FC8
move.b (Al)+, (A0) +
dbra D0,$FC230C
rts
FC2314 8001121A dc.b $80, $01, $12, $1A
Start data for iorec
14 bytes
Copy to RAM
Pointer to BIOS keyboard table
Keyboard ACIA control, master reset
/ 64 , 8 Bit, 1 stop bit, no parity
Pointer to MFP interrupt vectors
Initialize 4 vectors
Interrupt number
plus offset
Get vector from table
initint, install interrupt
Next vector
MIDI and keyboard vector
Vector number 6
initint, install interrupt
CTS interrupt routine
Vector number 2
initint, install interrupt
Pointer to init data for IKBD
4 bytes
Send string to IKBD
Block move
Next byte
Reset Keyboard, disable mouse + joystick
Abacus Software Atari ST Internals
358
FC2318
OOOOOCOE
dc . 1
$C0E
FC231C
0100
dc .w
$100
FC231E
0000
dc .w
0
FC2320
0000
dc . w
0
FC2322
0040
dc . w
$40
FC2322
ooco
dc .w
$C0
FC2326
000O0D0E
dc . 1
$D0E
FC232A
0080
dc .w
$80
FC232C
0000
dc .w
0
FC232E
0000
dc.w
0
FC2330
0020
dc.w
$20
FC2332
0060
dc.w
$60
FC2334
00000A0E
dc.l
$A0E
FC2338
0100
dc.w
$100
FC233A
0000
dc.w
0
FC233C
0000
dc.w
0
FC233E
0040
dc.w
$40
FC2340
OOCO
dc.w
$C0
FC2342
00000B0E
dc . 1
$B0E
FC2346
0100
dc.w
$100
FC2348
0000
dc.w
0
FC234A
0000
dc.w
0
FC234C
0040
dc.w
$40
FC234E
OOCO
dc . w
$C0
FC2350
00
dc .b
0
iorec for keyboard
Buffer address
Buffer size
Head index
Tail index
Low-water mark
High-water mark
iorec for MIDI
Buffer address
Buffer size
Head index
Tail index
Low-water mark
High-water mark
iorec for RS 232 input
Buffer address
Buffer size
Head index
Tail index
Low-water mark
High-water mark
iorec for RS 232 output
Buffer address
Buffer size
Head index
Tail index
Low-water mark
High-water mark
rsrbyte, receiver status
Abacus Software Atari ST Internals
to
VO
FC2351
00
dc . b
0
tsrbyte, transmitter status
FC2352
00
dc .b
0
rxof f
FC2353
00
dc .b
0
txof f
FC2354
01
dc . b
1
rsmode, XON/XOFF mode
FC2355
00
dc .b
0
filler
********************************************************
Interrupt vectors for MFP
FC2356
00FC2718
dc.l
5FC2718
#9, transmitter error
FC235A
00FC2666
dc.l
$FC2 666
#10, transmitter interrupt
FC235E
00FC26FA
dc . 1
$FC2 6FA
#11, receiver error
FC2362
00FC2596
dc . 1
$FC2596
#12, receiver interrupt
***********************************
*********************
setimer, initialize timer in MFP
FC2366
4 8E7F8F0
movem . 1
DO -D 4 /A0 -A3, - (A7)
Save registers
FC236A
2 07CFFFFFA01
move . 1
#$FFFFFA01 , A0
Address of MFP
FC2370
2 67COOFC23FA
move . 1
#$FC2 3FA, A3
Timer interrupt mask bit
FC2376
247COOFC23FE
move . 1
#$FC23FE,A2
FC237C
615A
bsr
$FC23D8
mskreg
FC237E
267C00FC23EE
move . 1
#$FC23EE, A3
Timer interrupt enable bit
FC2384
247C00FC23FE
move . 1
#$FC23FE, A2
FC238A
614C
bsr
$FC23D8
mskreg
FC238C
267C00FC23F2
move . 1
#$FC23F2, A3
Timer interrupt pending bit
FC2392
247C00FC23FE
move . 1
#$FC23FE, A2
FC2398
613E
bsr
$FC23D8
mskreg
FC239A
267C00FC23F6
move . 1
#$FC23F6, A3
Timer interrupt in-service bit
FC23A0
247C00FC23FE
move . 1
#$FC23FE,A2
FC23A6
6130
bsr
$FC23D8
mskreg
FC23A8
2 67C00FC2 4 02
move . 1
#$FC2402, A3
Timer control bit
FC23AE
247C00FC2406
move . 1
#$FC2 4 06, A2
FC23B4
6122
bsr
$FC23D8
mskreg
FC23B6
C7 4 9
exg
>
00
>
*->
Save A3
FC23B8
47F900FC240A
lea
$FC2 4 0A, A3
Address of timer data register
Abacus Software Atari ST Internals
360
FC23BE
7600
moveq . 1
#0, D3
FC23C0
16330000
move . b
0 (A3 , DO . w) ,D3
FC23C4
11823000
move . b
D2 , 0 (A0, D3 .w)
FC23C8
B4 303000
cmp.b
0 ( A0, D3 . w) ,D2
FC23CC
66F6
bne
$FC23C4
FC23CE
C74 9
exg
A3, A1
FC23D0
8313
or .b
Dl, (A3)
FC23D2
4CDF0F1F
movem. 1
(A7 ) +, D0-D4 /A0
FC23D6
4E75
rts
**************************************************
FC23D8
6106
bsr
$FC23E0
FC23DA
1612
move . b
(A2 ) ,D3
FC23DC
C713
and.b
D3, (A3)
FC23DE
4E75
rts
**************************************************
FC23E0
7600
moveq. 1
#0, D3
FC23E2
D6C0
add. w
DO, A3
FC23E4
1613
move . b
(A3) ,D3
FC23E6
D688
add. 1
A0, D3
FC23E8
2643
move . 1
D3, A3
FC23EA
D4C0
add . w
DO, A2
FC23EC
4E7 5
rts
**************************************************,
FC23EE
06060808
dc .b
6, 6 , 8 , 8
FC23F2
0A0A0C0C
dc .b
10,10,12,12
FC23F6
OEOEIOIO
dc .b
14,14,16,16
FC23FA
12121414
dc . b
18,18,20,20
Get register number
Write data in MFP
and read
until match
Restore A3
Mask timer control register
Restore registers
mskreg
getmask
Load mask
and clear bit (s)
getmask
Base plus register number
yields address offset in MFP
plus address of MFP
to A3
Pointer to the mask
MFP register numbers
iera, iera, ierb, ierb
ipra, ipra, iprb, iprb
isra, isra, isrb, isrb
imra, imra, imrb, imrb
i cn
Abacus Software Atari ST Internal!
OJ
On
FC23FE
DFFEDFEF
dc .b
$DF, $FE, $DF , $EF
FC2402
181A1C1C
dc.b
$18,$1A,$1C,$1C
FC2406
00008FF8
dc .b
0, 0 , $8F, $F8
FC240A
1E202224
dc.b
$1E, $20, $22, $24
******************************************************'
FC240E
302F0004
move . w
4 ( A7 ) , DO
FC2412
2 4 6F0006
move . 1
6 ( A7 ) ,A2
FC2416
02800000000F
and. 1
#15, DO
******************************************************
FC241C
48E7E0E0
movem. 1
D0-D2/A0-A2 , - (A7 )
FC2420
6120
bsr
$FC2442
FC2422
2400
move . 1
DO, D2
FC2424
E542
asl.w
#2 , D2
FC2426
068200000100
add. 1
#$100, D2
FC242C
2242
move . 1
D2,A1
FC242E
228A
move . 1
A2 , (Al)
FC2430
614A
bsr
$FC247C
FC2432
4CDF0707
movem . 1
(A7 ) +, D0-D2/A0-A2
FC2436
4E75
rts
***************************
***************************
FC2438
302F0004
move . w
4 ( A7 ) , DO
FC243C
02800000000F
and. 1
#15, DO
FC2442
48E7COCO
movem . 1
D0-D1/A0-A1, - (A7)
FC2446
4 1F9FFFFFA01
lea
$FFFFFA01 , A0
FC244C
43E80012
lea
18 (A0) , Al
FC2450
614A
bsr
$FC249C
FC2452
0391
bclr
Dl, (Al)
FC2454
43E80006
lea
6 (A0) , Al
Masks for MFP registers
Clear bits 5, 0, 5, 0
Set bits 3+4, bits 1,3+4, bits 2-4, bits 2-4
none, none, clear bits 5-7, bits 0-2
Set bits 2-4, bits 5, bits 1+5, bits 2+5
mfpint, set MFP interrupt vector
Interrupt number
Interrupt vector
Number 0-15, long word
initint, set MFP interrupt vector
Save registers
Disable interrupts
Vector number
As index for long word
Plus base address of the MFP vectors
Vector address
Set new vector
Enable interrupts
Restore registers
disint, disable MFP interrupt
Get interrupt number
as long word index
Save registers
Address of mfp
Address of imra
Calculate bit number to clear
And clear bit
Address of iera
Abacus Software Atari ST Internals
362
FC2458
6142
bsr
$FC2 4 9C
Calculate bit number
to
clear
FC245A
0391
bclr
Dl, (Al)
And clear bit
FC245C
4 3E8000A
lea
10 (A0) , Al
Address of ipra
FC2460
613A
bsr
$FC249C
Calculate bit number
to
clear
FC2462
0391
bclr
Dl, (Al)
And clear bit
FC2464
43E8000E
lea
14 (A0) , Al
Address of isra
FC2468
6132
bsr
$FC249C
Calculate bit number
to
clear
FC246A
0391
bclr
Dl, (Al)
and clear bit
FC246C
4CDF0303
movem . 1
(A7 ) +, D0-D1/A0-A1
Restore registers
FC2470
4E75
rts
*************************,********************,*********
jenabint, enable MFP
interrupt
FC2472
302F0004
move . w
4 (A7) , DO
Vector number
FC2476
02800000000F
and. 1
#15, DO
as long word index
FC247C
4 8E7C0C0
movem. 1
D0-D1/A0-A1,-(A7)
Save registers
FC2480
41F9FFFFFA01
lea
$FFFFFA01 , A0
Address of the MFP
FC2486
43E80006
lea
6 ( AO ) , Al
Address of iera
FC248A
6110
bsr
$FC249C
Calculate bit number
to
set
FC248C
03D1
bset
Dl, (Al)
and set bit
FC248E
43E80012
lea
18 (AO) , Al
Address of imra
FC2492
6108
bsr
$FC249C
Calculate bit number
to
set
FC2494
03D1
bset
Dl, (Al)
and set bit
FC2496
4CDF0303
movem . 1
(A7 ) +, DO-D1/AO-A1
Restire registers
FC249A
4E7 5
rts
******************************************************** bselect , determine bit and register number
FC249C
1200
move . b
DO, Dl
Save interrupt number
FC249E
0C000008
cmp.b
#8, DO
Greater than 8 ?
FC24A2
6D02
bit
$FC2 4A6
No
FC24A4
5141
subq . w
#8, Dl
Else subtract offset
FC24A6
0C000008
cmp . b
#8, DO
Greater than 8 ?
FC24AA
6C02
bge
$FC2 4AE
Yes
Abacus Software Atari ST Internals
FC24AC 5449
FC24AE 4E75
addq.w #2,A1
rts
****************************** *********************
FC24B0
4 1F900000D8E
lea
$D8E, A0
FC24B6
43F9FFFFFA01
lea
$FFFFFA01, A1
FC24BC
4E7 5
rts
**********************************'
*****************
FC24BE
34280008
move . w
8 (A0) , D2
FC24C2
36280006
move . w
6 (A0) ,D3
FC24C6
B443
cmp.w
D3,D2
FC24C8
6204
bhi
$FC24CE
FC24CA
D4 680004
add.w
4 (A0) ,D2
FC24CE
9443
sub.w
D3,D2
FC24D0
4E75
rts
**************************************************
FC24D2
082800010020
btst
#1,32 (A0)
FC24D8
6704
beq
$FC24DE
FC24DA
610008A8
bsr
$FC2D84
FC24DE
4E75
rts
**********************************
•A***************
FC24E0
40E7
move . w
SR, - (A7 )
FC24E2
007C0700
or .w
#$700, SR
FC24E6
61C8
bsr
$FC2 4B0
FC24E8
082800000020
btst
#0,32 (A0)
FC24EE
6706
beq
$FC24F6
FC24F0
4A28001F
tst .b
31 (A0)
FC24F4
6618
bne
$FC250E
FC24F6
08290007002C
btst
#7,44 (Al)
Pointer from A to B register
rs232ptr
Pointer to RS 232 iorec
Address of the MFP
rs232ibuf, determine buffer contents
Tail index
Head index
Head > tail ?
No
Add buffer size
Determine buffer contents
rtschk
RTS/CTS mode ?
No
rtson
r s232put, RS 232 output
Save status
IPL 7, disable interrupts
rs232ptr, get RS 232 buffer pointer
XON/XOFF mode?
No
XON active ?
Yes
Is MFP still sending ?
Abacus Software Atari ST Internals
FC24FC
6710
beq
5FC250E
FC24FE
34280014
move . w
20 (A0) ,D2
FC2502
B4 68001 6
cmp.w
22 (A0) ,D2
FC2506
6606
bne
$FC250E
FC2508
1341002E
move . b
Dl, 46 (Al)
FC250C
601A
bra
$FC2528
FC250E
34280016
move . w
22 (A0) ,D2
FC2512
610002FC
bsr
SFC2810
FC2516
B4 680014
cmp.w
20 (A0) ,D2
FC251A
6716
beq
$FC2532
FC251C
2268000E
move . 1
14 (A0) , Al
FC2520
13812000
move . b
Dl , 0 ( Al, D2 . w)
FC2524
31420016
move . w
D2 , 22 (A0)
FC2528
61A8
bsr
$FC24D2
FC252A
4 6DF
move . w
(A7 ) +, SR
FC252C
023C00FE
and.b
#$FE, SR
FC2530
4E75
rts
FC2532
619E
bsr
$FC24D2
FC2534
4 6DF
move . w
(Al) +, SR
FC2536
003C0001
or .b
#1 , SR
FC253A
4E75
rts
*************************************************
FC253C
40E7
move . w
SR, - (A7 )
FC253E
007C0700
or . w
#$700, SR
FC2542
6100FF6C
bsr
$FC24B0
FC2546
32280006
move . w
6 (A0) , Dl
FC254A
B2680008
cmp.w
8 (A0) , Dl
FC254E
67 1A
beq
$FC256A
FC2550
610002B2
bsr
$FC2804
FC2554
22680000
move . 1
(A0) , Al
Yes
Head index
Compare with tail index
Characters still in buffer
Byte into MFP transmitter register
Tail index
Test for wrap arround
Compare with head index
Buffer full?
Pointer to send buffer
Write byte in buffer
Save new tail index
rtschk, set RTS ?
Restore status
OK, clear carry flag
rtschk, set RTS?
Restore status
No output, set carry flag
rs232get, RS 232 input
Save status
IPL 7, disable interrupts
rs232ptr, get RS 232 pointer
Head index
Compare with tail index
Receiver buffer empty?
Test for wrap arround
Get buffer address
Abacus Software Atari ST internals
FC2558
7000
moveq . 1
O
D
o
FC255A
10311000
move . b
0(Al,Dl.w) , DO
FC255E
31410006
move . w
Dl, 6 (A0)
FC2562
4 6DF
move . w
( A7 ) + , SR
FC2564
023C00FE
and . b
#$FE, SR
FC2568
6006
bra
$FC2570
FC256A
4 6DF
move . w
(A7 ) +, SR
FC256C
003C0001
or .b
#1, SR
FC2570
082800000020
btst
#0,32 (A0)
FC2576
67 1C
beq
$FC2594
FC2578
4A28001E
tst . b
30 (A0)
FC257C
6716
beq
$FC25 94
FC257E
6100FF3E
bsr
$FC2 4BE
FC2582
B468000A
cmp . w
10 (A0) ,D2
FC2586
660C
bne
$FC2594
FC2588
123C0011
move .b
#$11, Dl
FC258C
6100FF52
bsr
$FC24E0
FC2590
4228001E
clr .b
30 (A0)
FC2594 4E75 rts
***************
FC2596
4 8E7FOEO
movem . 1
D0-D3/A0-A2 , -
FC259A
6100FF14
bsr
$FC24B0
FC259E
1169002A001C
move . b
42 (Al) ,28 (A0)
FC25A4
08280007001C
btst
#7, 28 (A0)
FC25AA
67 0000AE
beq
$FC2 65A
FC25AE
082800010020
btst
#1,32 (A0)
FC25B4
6704
beq
$FC25BA
FC25B6
610007C8
bsr
$FC2D80
FC25BA
1029002E
move . b
46 (Al) , DO
FC25BE
082800010020
btst
#1,32 (A0)
FC25C4
6640
bne
$FC2606
Get character from buffer
Save new head index
Restore status
Character there, clear carry flag
Restore status
No character, set carry flag
XON/XOFF mode?
No
XON active ?
No
Get input buffer length
Equals low-water mark?
No
XON
Send
Clear XON flag
rcvint, RS 232 receiver interrupt
Save registers
rs232ptr, get RS 232 pointer
Save receiver status register
Interrupt through receiver buffer full ?
No, ignore interrupt
RTS/CTS mode?
No
rtsof f
Read received byte
RTS/CTS mode?
Yes
Abacus Software Atari ST Internals
366
FC25C6 082800000020
FC25CC 6738
FC25CE OCOOOOll
FC25D2 6624
FC25D4 117C0000001F
FC25DA 34280014
FC25DE B4 68001 6
FC25E2 6776
FC25E4 6100022A
FC25E8 2 4 68000E
FC25EC 13722000002E
FC25F2 31420014
FC25F6 6062
FC25F8 0C000013
FC25FC 6608
FC25FE 1 17C00FFO01F
FC2604 6054
FC2606 32280008
FC260A 610001F8
FC260E B2680006
FC2612 6746
FC2614 24680000
FC2618 15801000
FC261C 31410008
FC2620 6100FE9C
FC2624 B468000C
FC2628 6624
FC262A 082800010020
FC2630 6628
FC2632 082800000020
FC2638 6714
FC263A 4A28001E
btst
#0, 32 (A0)
beq
$FC2 606
cmp.b
#17, DO
bne
$FC25F8
move . b
#0,31 (A0)
move . w
20 (A0) ,D2
cmp. w
22 (A0) ,D2
beq
$FC2 65A
bsr
$FC2810
move . 1
14 (A0) , A2
move . b
0 (A2 , D2 . w) , 46 (Al)
move . w
D2, 20 (A0)
bra
SFC265A
cmp.b
#19, DO
bne
$FC2606
move . b
#$FF, 31 (A0)
bra
$FC2 65A
move . w
8 (A0) ,D1
bsr
$FC2 804
cmp.w
6 (A0) ,D1
beq
$FC2 65A
move . 1
(A0) ,A2
move . b
DO, 0 (A2, D1 ,w)
move . w
Dl, 8 (A0)
bsr
$FC2 4BE
cmp . w
12 (A0) ,D2
bne
$FC2 64E
btst
#1,32 (A0)
bne
$FC2 65A
btst
#0,32 (A0)
beq
$FC264E
tst.b
30 (A0)
XON/XOFF mode?
No
XON received?
No
Clear XOFF flag
Head index sender
Compare with tail index sender
Send buffer empty?
Test for wrap around
Pointer to send buffer
Byte in MFP transmitter register
Save new head index
XOFF received ?
No
Set XOFF flag
Tail index
Test for wrap arround
Receiver buffer full?
Yes, ignore characters
Pointer to input buffer
Received charcter in buffer
Save new tail index
Get input buffer length used
Same as high-water mark?
No
RTS/CTS mode?
No
XON/XOFF mode?
No
XOFF already sent?
Abacus Software Atari ST Internals
367
FC263E 660E
FC2640 117C0OFFOO1E
FC2646 123C0013
FC264A 6100FE94
FC264E 082800010020
FC2654 6704
FC2656 6100072C
FC265A 08A90004000E
FC2660 4CDF070F
FC2664 4E73
***************************
FC2666 48E720E0
FC266A 6100FE44
FC266E 082800010020
FC2674 6630
FC2676 082800000020
FC267C 6706
FC267E 4A28001F
FC2682 6622
FC2684 1169002C001D
FC268A 34280014
FC268E B4 680016
FC2692 6712
FC2694 6100017A
FC2698 2468000E
FC269C 13722000002E
FC26A2 31420014
FC26A6 08A90002000E
FC26AC 4CDF0704
FC26B0 4E73
bne
$FC2 64 E
move . b
#$FF, 30 (A0)
move . b
#$13, D1
bsr
$FC24E0
btst
#1,32 (A0)
beq
$FC2 65A
bsr
$FC2D84
bclr
#4 , 14 ( A1 )
movem . 1
rte
(A7) +, D0-D3/A0-A2
movem . 1
D2/A0-A2 , - (A7)
bsr
$FC24B0
btst
#1,32 (A0)
bne
$FC2 6A6
btst
#0,32 (A0)
beq
$FC2 684
tst.b
31 (A0)
bne
$FC2 6A6
move . b
44 (Al) , 2 9 ( A0)
move . w
20 (A0) ,D2
cmp.w
22 (A0) ,D2
beq
$FC2 6A6
bsr
$FC2810
move . 1
14 (A0) ,A2
move .b
0(A2,D2.w) ,46 (Al)
move . w
D2, 20 (A0)
bclr
#2,14 (Al)
movem. 1
(A7) +, D2/A0-A2
rte
Yes
Flag for setting XOFF
XOFF
send
RTS/CTS mode?
No
rtson
Clear interrupt service bit
Restore registers
txrint, transmitter buffer empty
Save registers
rs232ptr, get RS 232 pointer
RTS/CTS mode?
Yes, then use this interrupt
XON/XOFF mode?
No
XOFF active ?
Yes, do nothing
Save transmitter status register
Head index
Compare with tail index
Send buffer empty?
Test for wrap around
Pointer to send buffer
Byte in MFP transmitter register
Save new head index
Clear interrupt service bit
Restore registers
ki
Abacus Software Atari ST Internals
CO
On
OO
***************************
FC26B2 48E720E0
FC26B6 6100FDF8
FC26BA 082800010020
FC26C0 672A
FC26C2 1169002C001D
FC26C8 08280007001D
FC26CE 67F8
FC26D0 34280014
FC26D4 B4680016
FC26D8 67 IE
FC26DA 61000134
FC26DE 24 68000E
FC26E2 13722000002E
FC26E8 31420014
FC26EC 08A900020010
FC26F2 4CDF0704
FC26F6 4E73
c****************************
movem.l D2/A0-A2 , - (A7)
bsr $FC24B0
btst #1,32 (A0)
beq $FC2 6EC
move.b 44 (Al) , 2 9 ( AO)
btst #7, 29 (A0)
beq $FC2 6C8
move.w 20 (A0) ,D2
cmp. w 22 (A0) , D2
beq $FC2 6F8
bsr $FC2810
move . 1 14 ( A0 ) , A2
move.b 0 (A2,D2.w) , 46 (Al)
move.w D2, 20 (A0)
bclr #2 , 1 6 (Al )
movem.l (A7) +, D2/A0-A2
rte
FC26F8 60F2
***************************
FC26FA 4 8E7 80C0
FC26FE 6100FDB0
FC2702 1169002A001C
FC2708 1029002E
FC270C 08A90003000E
FC2712 4CDF0301
FC2716 4E73
bra $FC2 6EC
r ****************************
movem.l D0/A0-A1, - (A7)
bsr $FC24B0
move.b 42 (Al) , 28 (A0)
move.b 46(A1),D0
bclr #3, 14 (Al)
movem.l (A7 ) +, D0/A0-A1
rte
********************************************************
FC2718 48E700C0 movem.l A0-A1,-(A7)
FC271C 6100FD92 bsr $FC24B0
ctsint, CTS interrupt routine
Save registers
rs232ptr, get RS 232 pointer
RTS/CTS mode?
No, ignore interrupt
Save transmitter status
Transmitter buffer empty ?
No, wait (must jump to $FC26C2!)
Head index
Compare with tail index
Send buffer empty
Test for wrap around
Pointer to send buffer
Byte in MFP transmitter register
Save new head index
Clear interrupt service bit
Restore registers
Send buffer empty
rxerror, RS 232 receiver error
Save registers
rs232ptr, get RS 232 pointer
Save receiver status
Read data register (clear status)
Clear interrupt service bit
Restore registers
txerror, RS 232 send error
Save registers
rs232ptr, get RS 232 pointer
FC2720 1169002C001D
FC2726 08A90001000E
FC272C 4CDF0300
FC2730 4E73
move.b 44 (Al) , 29 (AO)
bclr #1 , 14 ( Al )
movem.l (A71+/A0-A1
rte
FC2732 7200
FC2734 322F0004
FC2738 40E7
FC273A 007C0700
FC273E 45F900FC274E
FC2744 E581
FC2746 20321800
FC274A 4 6DF
FC274C 4E75
moveq.l #0,D1
move.w 4 (A7) ,D1
move.w SR, — ( A7 )
or .w #$700, SR
lea $FC2 7 4E, A2
asl.l #2 , D1
move . 1 0 (A2 , D1 . 1) , DO
move . w (A7 ) +, SR
********************************************************
FC274E 00000D8E dc.l $D8E
FC2752 OOOOODBO dc.l $DB0
FC2756 00000DBE dc.l $DBE
***************************
FC275A 007C0700
FC275E 6100FD50
FC2762 0F490028
FC2766 4A6F0006
FC276A 6B0A
FC276C 116F00070020
FC2772 7000
FC2774 7400
FC2776 4A6F0004
FC277A 6B34
****************************
or .w #$700, SR
bsr $FC24B0
movep.l $28(A1),D7
tst.w 6(A7)
bmi $FC2776
move.b 7(A7),32(A0)
moveq.l #0,D0
moveq.l #0,D2
tst.w 4 (A7)
bmi $FC27B0
Save transmitter status
Clear interrupt service bit
Restore registers
get iorec
Device number
Save status
IPL 7, disable interrupts
Address of the table
Long access
Get pointer to iorec
Restore status
iorec table
RS 232
IKBD
MIDI
rsconf, configure RS 232
IPL 7, disable interrupts
rs232ptr, get RS 232 pointer
Save ucr, rsr, tsr and scr
Mode
Negative, don't reset
Reset rsmode
Baud rate
Negative, don't change
Abacus Software Atari ST Internals
370
FC277C 7000
FC277E 1340002A
FC2782 1340002C
FC2786 322F0004
FC278A 45F900FC27E4
FC2790 10321000
FC2794 45F900FC27F4
FC279A 14321000
FC279E 2200
FC27A0 7003
FC27A2 6100FBC2
FC27A6 7001
FC27A8 1340002A
FC27AC 1340002C
FC27B0 4A6F0008
FC27B4 6B0 6
FC27B6 136F00090028
FC27BC 4A6F000A
FC27C0 6B06
FC27C2 136F000B002A
FC27C8 4A6FOOOC
FC27CC 6B06
FC27CE 136F000D002C
FC27D4 4A6F000E
FC27D8 6B06
FC27DA 13 6F0 00F002 6
FC27E0 2007
FC27E2 4E75
moveq.l #0,D0
move .b DO, 42 (Al)
move.b DO, 44 (Al)
move . w 4 (A7 ) , D1
lea $FC27E4,A2
move.b 0 ( A2 , D1 . w) , DO
lea $FC27F4,A2
move.b 0 (A2, D1 .w) , D2
move . 1 D0,D1
moveq.l #3, DO
bsr $FC2366
moveq.l #1,D0
move .b DO, 42 (Al)
move.b DO, 44 (Al)
tst.w 8 ( A7 )
bmi $FC27BC
move.b 9(A7),40(A1)
tst.w 10(A7)
bmi $FC27C8
move.b 11 (A7) , 42 (Al)
tst.w 12 ( A7 )
bmi $FC27D4
move.b 13 (A7) , 44 (Al)
tst.w 14 (A7)
bmi $FC27E0
move.b 15 ( A7 ) , 38 ( Al )
move . 1 D7,D0
rts
FC27E4 0101010101010101 dc.b
FC27EC 0101010101010202 dc.b
1,1, 1,1, 1,1, 1,1
1,1, 1,1, 1,1, 2, 2
\
Disable receiver
Disable sender
Get new baud rate
Table of timer values, control registers
Get value
Table of timer values, data registers
Get value
Pointer to timer D
Set timer D for new baud rate
Enable receiver
Enable sender
Set ucr ?
No
New ucr value
Set rsr ?
No
New rsr value
Set tsr?
No
New tsr value
Set scr?
No
Set scr
old value for control register
Timer values for RS 232 baud rate
Control register
1 = /4, 2 = /10
Abacus Software Atari ST Internals
Oi
FC27F4
01020405080 AO BIO
dc . b
1,2,4,5,8,10,11,16
Data register
FC27FC
2 0 4 0 60808FAFF 4 0 60
dc . b
32,64, 96, 128,143, 175,
64, 96
★*★★*★*
:****************************
*********************
wrapin, test for wrap around
FC2804
5241
addq . w
#1, D1
Head index + 1
FC2806
B2 680004
cmp . w
4 (A0) ,D1
Equals buffer size?
FC280A
6502
bcs
$FC280E
No
FC280C
7200
moveq . 1
#0, D1
Else begin with zero
FC280E
4E7 5
rts
***********************************
*********************
wrapout, test for wrap around
FC2810
5242
addq . w
#1 , D2
Tail index + 1
FC2812
B4 680012
cmp . w
18 (A0) ,D2
Equals buffer size?
FC2816
6502
bcs
$FC281A
No
FC2818
7400
moveq. 1
#0, D2
Else begin with zero
FC281A
4E7 5
rts
********************************************************
midikey, keyboard and MIDI interrupt
FC281C
4 8E7F0F4
movem . 1
DO-D3/AO-A3/A5, - <A7)
Save registers
FC2820
4 BF 900000000
lea
$0, A5
Clear A5
FC2826
246D0DE8
move . 1
$DE8 (A5) ,A2
mbufrec, MIDI
FC282A
4E92
jsr
(A2 )
Interrupt from MIDI ACIA ?
FC282C
24 6D0DEC
move . 1
$DEC(A5) ,A2
kbufrec, keyboard
FC2830
4E92
jsr
(A2 )
Interrupt from keyboard ACIA ?
FC2832
08390004FFFFFA01
btst
#4, $FFFFFA01
mfp gpip, still an interrupt there?
FC283A
67EA
beq
$FC282 6
Yes, proces
FC283C
08B90006FFFFFA11
bclr
#6, 5FFFFFA11
Clear interrupt service bit
FC2844
4CDF2F0F
movem . 1
(A7) +, D0-D3/A0-A3/A5
Restore registers
FC2848
4E7 3
rte
$DBE ( A5) , AO
midisys, MIDI interrupt
iorec for MIDI
FC284A 4 1ED0DBE
lea
Abacus Software Atari ST Internals
372
r
FC284E
4 3F9FFFFFC04
lea
$FFFFFC04, Al
FC2854
24 6D0DD4
move . 1
$DD4 ( A5) , A2
FC2858
600E
bra
$FC2868
******************************************************
FC285A
41ED0DB0
lea
$DB0 (A5) , A0
FC285E
43F9FFFFFC00
lea
$FFFFFC00, A1
FC2864
246D0DD0
move . 1
$DD0 (AS) , A2
FC2868
14290000
move . b
(Al) ,D2
FC286C
08020007
btst
#7 , D2
FC2870
671C
beq
$FC288E
FC2872
08020000
btst
#0, D2
FC2876
670A
beq
SFC2882
FC2878
48E720E0
movem. 1
D2/A0-A2, - (A7)
FC287C
6112
bsr
$FC2890
FC287E
4CDF0704
movem . 1
(A7 ) +, D2/A0-A2
FC2882
02020020
and.b
#$20, D2
FC2886
6706
beq
$FC288E
FC2888
10290002
move . b
2 (Al) , DO
FC288C
4ED2
jmp
(A2 )
FC288E
4E75
rts
******************************************************,
FC2890
10290002
move . b
2 (Al) , DO
FC2894
B1FCOOOOODBO
cmp. 1
#$DB0, A0
FC289A
66000440
bne
$FC2CDC
FC289E
4A2D0DF0
tst .b
$DF0 ( A5)
FC28A2
6660
bne
$FC2 904
FC28A4
0C0000F6
cmp.b
#$F6, DO
FC28A8
65000100
bcs
SFC29AA
FC28AC
040000F6
sub.b
#$F6, DO
FC28B0
0280000000FF
and, 1
#$FF, DO
MIDI ACIA control
MIDI error routine
ikbdsys, keyboard interrupt
iorec for keyboard
Keyboard ACIA control
Keyboard error routine
Get ACIA status
Interrupt request ?
No
Receiver buffer full?
No
Save registers
arcvint, get byte
Restore registers
Clear tested bit
No error
Read data again, clear status
Execute error routine
arcvint, get byte from ACIA
get data from ACIA
Keyboard ACIA ?
No, MIDI
Keyboard state
Keypress ?
yes
Subtract offset
Abacus Software Atari ST Internals
FC28B6
4 7F900FC2 8F0
lea
$FC28F0, A3
FC28BC
1B7 30 OOOODFO
move . b
0 (A3, DO .w) , $DF0 (A5)
FC28C2
47F900FC28FA
lea
$FC2 8FA, A3
FC28C8
1B7300000DF1
move . b
0 (A3, DO . w) , $DF1 ( A5)
FC28CE
064000F6
add.w
#$F6, DO
FC28D2
0C0000F8
cmp.b
#$F8 , DO
FC28D6
6D0C
bit
$FC2 8E4
FC28D8
OCOOOOFB
cmp.b
#$FB, DO
FC28DC
6E0 6
bgt
$FC2 8E4
FC28DE
1B400DFE
move . b
DO, $DFE(A5)
FC28E2
4E7 5
rts
FC28E4
0C0000FD
cmp.b
#$FD, DO
FC28E8
6D04
bit
$FC2 8EE
FC28EA
1B400E07
move . b
DO, $E07 (A5)
FC28EE
4E7 5
rts
*******************************************************
FC28F0
01020303030304050607
dc .b
1,2, 3, 3, 3, 3, 4, 5, 6, 7
FC28FA
07050202020206020101
dc.b
7, 5, 2, 2, 2, 2, 6, 2, 1,1
*******************************************************
FC2904
OC2D00060DF0
cmp.b
#6, $DF0 (A5)
FC290A
64000084
bcc
$FC2 990
FC290E
45F900FC2 954
lea
$FC2 95 4 , A2
FC2914
7400
moveq . 1
#0 , D2
FC2916
142D0DF0
move . b
$DF0 (A5) ,D2
FC291A
5302
subq.b
#1 , D2
FC291C
E342
asl.w
#1, D2
FC291E
D42D0DF0
add.b
$DF0 ( A5) ,D2
FC2922
5302
subq.b
. #1 , D2
FC2924
E542
asl.w
#2 , D2
FC2926
20722000
move . 1
0 ( A2 , D2 . w) , A0
Pointer to IKBD code table
Save IKBD
Pointer to IKBD length table
IKBD index
Add offset again
Mouse position record ?
No
Mouse position record ?
No
Save mouse position
Joystick record ?
No
Save joystick data
IKBD parameters
Status code for $F6-$FF
Length-1 for $F6-$FF
Joystick record ?
Yes
Pointer to IKBD parameter table
Kstate
1-5 => 0-4
times 2
plus once
IKBD record pointer
Abacus Software Atari ST Internals
374
FC292A
22722004
move . 1
4 (A2,D2.w) , A1
IKBD index base
FC292E
24722008
move . 1
8 ( A2 , D2 . w) , A2
IKBD interrupt routine
FC2932
2452
move . 1
(A2 ) ,A2
Get interrupt vector
FC2934
7400
moveq . 1
#0, D2
FC2936
142D0DF1
move . b
$DF1 ( A5) ,D2
Get IKBD index
FC293A
93C2
sub.l
D2 , A1
minus base
FC293C
1280
move . b
DO, (Al)
FC293E
532D0DF1
subq.b
#1, $DF1 (A5)
IKBD index minus 1
FC2942
4 A2D0DF1
tst.b
$DF1 (A5)
Test index
FC2946
660A
bne
$FC2952
FC2948
2F08
move . 1
A0, - (A7)
Pass record pointer
FC294A
4E92
jsr
(A2)
Execute interrupt routine
FC294C
584F
addq . w
#4,A7
Correct stack pointer
FC294E
422D0DF0
clr.b
$DF0 (A5)
Clear IKBD state
FC2952
4E75
rts
********************************************************
V
Parameter table for IKBD
FC2954
00000DF2
dc . 1
$DF2
FC2958
00000DF9
dc.l
$DF9
FC295C
00000DD8
dc . 1
$DD8
FC2960
00000DF9
dc.l
$DF9
FC2964
00000DFE
dc . 1
$DFE
FC2968
00000DDC
dc . 1
$DDC
FC296C
OOOOODFE
dc . 1
$DFE
FC2970
00000E01
dc . 1
$E01
FC2974
OOOOODDC
dc.l
$DDC
FC2978
OOOOOEOl
dc . 1
$E01
FC297C
00000E07
dc . 1
$E07
FC2980
OOOOODEO
dc . 1
$DE0
FC2984
000O0E07
dc.l
$E07
FC2988
00000E09
dc . 1
$E09
FC298C
00000DE4
dc . 1
$DE4
Abacus Software Atari ST Internals
375
FC2990
223C00000E08
move . 1
#$E08 , D1
FC2996
D22D0DF0
add . b
$DF0 ( A5) ,D1
FC299A
5D01
subq . b
#6,D1
FC299C
2441
move . 1
Dl, A2
FC299E
1480
move . b
DO, (A2)
FC29A0
2 4 6D0DE4
move . 1
$DE4 (A5) , A2
FC29A4
41ED0E07
lea
$E07 ( A5) , AO
FC29A8
609E
bra
$FC2948
FC29AA
122D0E1B
move . b
$E1B(A5)
FC29AE
0C00002A
cmp.b
#$2A, DO
FC29B2
6606
bne '
$FC2 9BA
FC29B4
08C10001
bset
#1 , Dl
FC29B8
6074
bra
$FC2A2E
FC29BA
OCOOOOAA
cmp.b
#$AA, DO
FC29BE
6606
bne
$FC2 9C6
FC29C0
08810001
bclr
#1 , Dl
FC29C4
6068
bra
$FC2A2E
FC29C6
OC000036
cmp.b
#$36, DO
FC29CA
6606
bne
$FC2 9D2
FC29CC
08C10000
bset
#0 , Dl
FC29D0
605C
bra
$FC2A2E
FC29D2
0C0000B6
cmp.b
#$B6, DO
FC29D6
6606
bne
$FC2 9DE
FC29D8
08810000
bclr
#0 , Dl
FC29DC
6050
bra
$FC2A2E
FC29DE
OC00001D
cmp.b
#$1D, DO
FC29E2
6606
bne
$FC2 9EA
FC29E4
08C10002
bset
#2 , Dl
FC29E8
6044
bra
$FC2A2E
Joystick 0 and 1
Joystick interrupt routine
Address of joystick data
Process keypress
Shift status
Left shift key pressed?
No
Set bit for left shift key
Left shift key released?
No
Clear bit for left shift key
Right shift key pressed?
No
Set bit for right shift key
Right shift key released?
No
Clear bit for right shift key
CTRL key pressed?
No
Set bit for CTRL key
Abacus Software Atari ST Internals
376
FC29EA
0C00009D
cmp . b
#$ 9D , DO
CTRL key released?
FC29EE
6606
bne
$FC2 9F6
No
FC29F0
08810002
bclr
#2 , D1
Clear bit for CTRL key
FC29F4
6038
bra
$FC2A2E
FC29F6
0C000038
cmp . b
#$38, DO
ALT key pressed?
FC29FA
6606
bne
$FC2A02
No
FC29FC
08C10003
bset
#3, D1
Set bit for ALT key
FC2A00
602C
bra
$FC2A2E
FC2A02
0C0000B8
cmp.b
#$B8 , DO
ALT key released?
FC2A06
6606
bne
$FC2A0E
No
FC2A08
08810003
bclr
#3, D1
Clear bit for ALT key
FC2A0C
6020
bra
$FC2A2E
FC2A0E
OC00003A
cmp.b
#$3A, DO
CAPS LOCK pressed ?
FC2A12
6620
bne
$FC2A34
No
FC2A14
082D00000484
btst
#0, $484 (A5)
conterm, key click ?
FC2A1A
670E
beq
$FC2A2A
No
FC2A1C
2B7CO0FC3O94OE44
move . 1
#$FC3094 , $E4 4 (A5)
Addres of key click sound
FC2A24
1B7COOOOOE48
move . b
#0, $E48 (A5)
Start sound
FC2A2A
08410004
bchg
#4 , D1
Invert CAPS LOCK status
FC2A2E
1B410E1B
move . b
Dl, $E1B (A5)
Save new shift status
FC2A32
4E75
rts
FC2A34
08000007
btst
#7, DO
Was key released?
FC2A38
662A
bne
$FC2A64
Yes
FC2A3A
4 A2D0E3 9
tst .b
$E3 9 ( A5)
Repeat ?
FC2A3E
6616
bne
$FC2A5 6
Yes
FC2A40
1B400E39
move . b
DO, $E39 (A5)
Save key code for repeat
FC2A44
1B7900000E3C0E3A
move . b
$E3C,$E3A(A5)
Delay 1
FC2A4C
1B7900000E3DOE3B
move . b
$E3D, $E3B (A5)
Delay 2
FC2A54
603A
bra
$FC2A90
Abacus Software Atari ST Internals
377
FC2A56
FC2A5C
FC2A62
FC2A64
FC2A68
FC2A6A
FC2A6C
FC2A70
FC2A74
FC2A78
FC2A7C
FC2A7E
FC2A82
FC2A86
FC2A8C
FC2A90
FC2A96
FC2A98
FC2AA0
FC2AA6
FC2AA8
FC2AAA
FC2AAC
FC2AB0
FC2AB4
FC2ABA
FC2ABC
FC2AC0
FC2AC6
FC2AC8
FC2ACE
FC2AD0
1B7C00000E3A
move . b
#0, $E3A(A5)
1B7C00000E3B
move .b
#0, $E3B(A5)
602C
bra
$FC2 A90
4A2D0E39
tst .b
$E3 9 ( A5)
67 0E
beq
$FC2A7 8
7200
moveq . 1
#0, D1
1B410E39
move . b
D1,$E39(A5)
1B410E3A
move . b
D1,$E3A(A5)
1B410E3B
move . b
Dl, $E3B(A5)
OCOOOOC7
cmp . b
#$C7 , DO
6708
beq
$FC2A8 6
OCOOOOD2
cmp.b
#$D2 , DO
66000256
bne
$FC2CDA
082D00030E1B
btst
#3, $E1B (A5)
6700024C
beq
$FC2CDA
082D00000484
btst
#0, $484 (A5)
670E
beq
$FC2AA6
2B7000FC30940E44
move . 1
#$FC3094,$E44(A5)
1B7COOOOOE4 8
move . b
#0, $E48 (A5)
2F08
move . 1
A0, - (A7)
7200
moveq . 1
#0, Dl
1200
move . b
DO, Dl
206D0E1C
move . 1
$E1C(A5) , A0
0240007F
and.w
#$7F , DO
082D00040E1B
btst
#4 , $E1B ( A5 )
6704
beq
$FC2 AC0
206D0E24
move . 1
$E24 ( A5) , A0
082DOOOOOE1B
btst
#0, $E1B (A5)
6608
bne
$FC2AD0
082D00010E1B
btst
#1 , $E1B ( A5)
67 1A
beq
$FC2AEA
0C00003B
cmp.b
#$3B, DO
Clear counter for delay 1
Clear counter for delay 2
Key for repeat?
No
Clear key code for repeat
Clear delay 1
Clear delay 2
HOME key released?
Yes
INSERT key released?
No
ALT key still pressed?
No
conterm, key click ?
No
Address of sound table for key click
Start sound
Save iorec for keyboard
Scancode to D1
Address of the standard keyboard table
Clear bit for released
CAPS LOCK active ?
No
Address of CAPS LOCK keyboard table
Right shift key pressed?
Yes
Left shift key pressed?
No
Function key ? (FI)
Abacus Software Atari ST Internals
FC2AD4 6510
FC2AD6 0C000044
FC2ADA 62 0A
FC2ADC 06410019
FC2AE0 7000
FC2AE2 600001B2
FC2AE6 206D0E20
FC2AEA 10300000
FC2AEE 082D00020E1B
FC2AF4 6760
FC2AF6 OCOOOOOD
FC2AFA 6604
FC2AFC 700A
FC2AFE 672A
FC2B00 0C010047
w FC2B04 6608
<! FC2B06 06410030
oo
FC2B0A 6000018A
FC2B0E 0C01004B
FC2B12 6608
FC2B14 7273
FC2B16 7000
FC2B18 6000017C
FC2B1C 0C01004D
FC2B20 6608
FC2B22 7274
FC2B24 7000
FC2B26 6000016E
FC2B2A 0C000032
FC2B2E 6606
FC2B30 7000
FC2B32 60000162
bcs
$FC2AE6
cmp.b
#$44, DO
bhi
$FC2 AE6
add . w
#$19, D1
moveq . 1
#0 , DO
bra
$FC2C96
move . 1
$E20(A5) , A0
move . b
0 ( A0 , DO . w) , DO
btst
#2, $E1B(A5)
beq
$FC2B56
cmp.b
#13, DO
bne
$FC2B00
moveq. 1
#10, DO
beq
$FC2B2 A
cmp.b
#$47, D1
bne
$FC2B0E
add.w
#$30, D1
bra
$FC2C96
cmp . b
#$4B,D1
bne
$FC2B1C
moveq. 1
#$73, D1
moveq . 1
#0 , DO
bra
$FC2C96
cmp . b
#$4D, D1
bne
$FC2B2 A
moveq . 1
#$74, D1
moveq. 1
o
Q
o
bra
$FC2C96
cmp . b
#$32, DO
bne
$FC2B36
moveq . 1
o
Q
o
=#=
bra
$FC2C96
No
Function key ? (F10)
No
Add offset to GSX standard
ASCII code equals zero
Address of the shift keyboard table
Get ASCII code from table
CTRL key table?
No
Carriage return?
No
Convert to linefeed
CTRL HOME?
No
Add offset to GSX standard
CTRL cursor left?
No
GSX standard
ASCII code zero
CTRL cursor right ?
No
GSX standard
ASCII code zero
CTRL M ?
ASCII code zero
Abacus Software Atari ST Internals
FC2B36
OC000036
cmp . b
#$36, DO
CTRL Shift ?
FC2B3A
6606
bne
$FC2 B4 2
FC2B3C
7 0 IE
moveq . 1
#$1E, DO
ASCI code RS
FC2B3E
60000156
bra
$FC2C96
FC2B42
OC00002D
cmp.b
#$2D, DO
CTRL C ?
FC2B46
6606
bne
$FC2B4E
FC2B48
701F
moveq . 1
#$ IF, DO
ASCII code US
FC2B4A
6000014A
bra
$FC2C96
FC2B4E
0240001F
and.w
#$1F, DO
Convert code to CTRL
code
FC2B52
60000142
bra
$FC2C96
FC2B56
082D00030E1B
btst
#3, $E1B(A5)
ALT key pressed?
FC2B5C
67000138
beq
$FC2C96
No
FC2B60
0C01001A
cmp . b
#2 6, D1
Key 'O' ?
FC2B64
6618
bne
$FC2B7E
No
FC2B66
103C0040
move . b
#$40, DO
i g i
FC2B6A
142D0E1B
move . b
$E1B(A5)
,D2
Shift status
FC2B6E
02020003
and.b
#3,D2
One of the shift keys
pressed?
FC2B72
67000122
beq
$FC2C96
No
FC2B76
103C005C
move . b
#$5C, DO
•V
FC2B7A
6000011A
bra
$FC2C96
FC2B7E
OC010027
cmp.b
#39, D1
Key '5' ?
FC2B82
6618
bne
$FC2B9C
FC2B84
103C005B
move . b
#$5B, DO
, [.
FC2B88
142D0E1B
move . b
$E1B(A5)
,D2
Shift status
FC2B8C
02020003
and.b
#3, D2
One of the shift keys
pressed?
FC2B90
67000104
beq
$FC2C96
No
FC2B94
103C007B
move . b
#$7B, DO
' {'
FC2B98
600000FC
bra
$FC2C96
FC2B9C
0C010028
cmp . b
#40, D1
Key 'A' ?
FC2BA0
6618
bne
$FC2BBA
No
FC2BA2
103C005D
move . b
#$5D, DO
FC2BA6
142D0E1B
move . b
$E1B(A5)
,D2
Shift status
Abacus Software Atari ST Internals
380
f
FC2BAA
02020003
and.b
#3, D2
FC2BAE
670000E6
beq
$FC2C96
FC2BB2
103C007D
move . b
#$7D, DO
FC2BB6
600000DE
bra
$FC2C96
FC2BBA
0C010062
cmp.b
#98, D1
FC2BBE
660A
bne
$FC2BCA
FC2BC0
52 6D04EE
addq . w
#1 , $4EE (A5)
FC2BC4
2 05F
move . 1
(A7) +, A0
FC2BC6
60000112
bra
$FC2CDA
FC2BCA
45F900FC2D48
lea
$FC2D48,A2
FC2BD0
7403
moveq . 1
#3 , D2
FC2BD2
B2322000
cmp.b
0(A2,D2.w) ,D1
FC2BD6
6700012C
beq
$FC2D04
FC2BDA
51CAFFF6
dbra
D2 , $FC2BD2
FC2BDE
0C010048
cmp.b
#$48, D1
FC2BE2
661C
bne
$FC2C00
FC2BE4
123COOOO
move . b
#0, D1
FC2BE8
143CFFF8
move . b
#-8,D2
FC2BEC
102D0E1B
move . b
$E1B(A5) , DO
FC2BF0
02000003
and.b
#3, DO
FC2BF4
6700012C
beq
$FC2D22
FC2BF8
143CFFFF
move . b
#-l,D2
FC2BFC
60000124
bra
$FC2D22
FC2C00
0C010O4B
cmp.b
#$4B,D1
FC2C04
661C
bne
$FC2C22
FC2C06
14 3C0000
move . b
#0, D2
FC2C0A
123CFFF8
move . b
#-8,Dl
FC2C0E
102D0E1B
move . b
$E1B(A5) , DO
FC2C12
02000003
and.b
#3, DO
FC2C16
6700010A
beq
$FC2D22
FC2C1A
123CFFFF
move . b
#— 1 , D1
One of the shift keys pressed?
No
' } '
ALT HELP ?
No
_dumpflg for hardcopy
Restore keyboard iorec
Pointer to mouse scancode table
Test four values
Value found?
Yes
Next value
Cursor up?
No
X-offset for cursor up
Y-offset for cursor up
Get shift status
One of the shift keys pressed?
No
Y-offset, only one pixel high
Cursor left ?
No
Y-offset for cursor left
X-offset for cursor left
Get shift status
One of the shift keys pressed?
No
X-offset, only one pixel left
Abacus Software Atari ST Internals
FC2C1E
60000102
bra
SFC2D22
FC2C22
0C01004D
cmp.b
#$4D, D1
Cursor right ?
FC2C26
6 6 1C
bne
$FC2C4 4
No
FC2C28
123C0008
move . b
#8, D1
X-offset for cursor right
FC2C2C
143C0000
move . b
#0 , D2
Y-offset for cursor right
FC2C30
102D0E1B
move . b
$E1B(A5)
, DO
Get shift status
FC2C34
02000003
and.b
#3, DO
One of the shift keys pressed?
FC2C38
670000E8
beq
$FC2D22
No
FC2C3C
123C0001
move . b
#1 , D1
X-offset, only one pixel right
FC2C40
600000E0
bra
$FC2D22
FC2C44
0C010050
cmp.b
#$50, D1
Cursor down ?
FC2C48
661C
bne
$FC2C66
No
FC2C4A
123C0000
move . b
#0, D1
X-offset for cursor down
FC2C4E
143C0008
move . b
#8 , D2
Y-offset for cursor down
FC2C52
102D0E1B
move . b
$E1B (AS)
, DO
Shift status
FC2C56
02000003
and.b
#3, DO
One of the shift keys pressed?
FC2C5A
670000C6
beq
$FC2D22
No
FC2C5E
143C0001
move . b
#1 , D2
Y-offset, only one pixel down
FC2C62
600000BE
bra
$FC2D22
FC2C66
0C010002
cmp.b
#2,D1
'1'
FC2C6A
650C
bcs
$FC2C78
FC2C6C
0C01000D
cmp.b
#13, D1
* = <
FC2C70
6206
bhi
$FC2C7 8
FC2C72
06010076
add.b
#118, D1
FC2C76
600C
bra
$FC2C84
FC2C78
0C000041
cmp . b
#65, DO
'A'
FC2C7C
650A
bcs
$FC2C88
FC2C7E
0C00005A
cmp.b
#90, DO
'Z'
FC2C82
6204
bhi
$FC2C88
FC2C84
7000
moveq. 1
#0 , DO
FC2C86
600E
bra
$FC2C96
FC2C88
0C000061
cmp.b
#97, DO
'a'
Abacus Software Atari ST Internals
382
FC2C8C
6508
bcs
$FC2C96
FC2C8E
0C00007A
cmp . b
#122, DO
FC2C92
6202
bhi
$FC2C96
FC2C94
60EE
bra
$FC2C84
FC2C96
El 4 1
asl.w
#8, D1
FC2C98
D041
add.w
D1 , DO
FC2C9A
205F
move . 1
(A7 ) +, AO
FC2C9C
32280008
move . w
8 (AO) ,D1
FC2CA0
5841
addq . w
#4 , D1
FC2CA2
B2 680004
cmp.w
4 (A0) ,D1
FC2CA6
6502
bcs
$FC2CAA
FC2CA8
7200
moveq . 1
#0, D1
FC2CAA
B2 68000 6
cmp.w
6 ( A0 ) ,D1
FC2CAE
672A
beq
$FC2CDA
FC2CB0
24680000
move . 1
(A0) ,A2
FC2CB4
4840
swap
DO
FC2CB6
303C0000
move .w
#0 , DO
FC2CBA
102D0E1B
move . b
$E1B(A5) , DO
FC2CBE
4840
swap
DO
FC2CC0
E188
lsl.l
#8, DO
FC2CC2
E048
lsr ,w
#8, DO
FC2CC4
082D000304 84
btst
#3, $484 ( A5 )
FC2CCA
6606
bne
$FC2CD2
FC2CCC
028000FFFFFF
and. 1
#$00FFFFFF, DO
FC2CD2
25801000
move . 1
DO, 0 ( A2 , D1 . w)
FC2CD6
31410008
move . w
Dl, 8 (A0)
FC2CDA
4E75
rts
move.l $DCC(A5),A2
jmp (A2)
' z'
Scancode to bits 8-15
plus ASCII code
iorec pointer to keyboard
Tail index
plus 4
End of buffer reached?
No
Start over again
Buffer full?
Yes, ignore data
Address of the buffer
ASCII code to bits 16-23
Shift status
in upper word
in bits 24-31
ASCII code to bits 0-7
conterm, accept shift status?
Yes
Clear shift status
Write data in keyboard buffer
Update buffer pointer
FC2CDC 2 4 6D0DCC
FC2CE0 4ED2
midibyte
Pointer to MIDI interrupt handler
Execute routine
Abacus Software Atari ST Internals
383
FC2CE2
32280008
move . w
8 (A0) , D1
Tail index
FC2CE6
5241
addq . w
#1,D1
Increment
FC2CE8
B2 680004
cmp . w
4 (A0) , D1
End of buffer reached?
FC2CEC
6502
bcs
$FC2CF0
No
FC2CEE
7200
moveq . 1
#0, D1
Buffer pointer back to buffer start
FC2CF0
B2 680006
cmp . w
6 (A0) ,D1
Head equals tail ?
FC2CF4
67 0C
beq
$FC2D02
Yes, buffer full
FC2CF6
24680000
move . 1
(A0) , A2
Buffer address
FC2CFA
15801000
move .b
DO, 0 (A2,Dl.w)
Write byte in buffer
FC2CFE
31410008
move . w
Dl, 8 (A0)
New tail index
FC2D02
4E7 5
rts
★ *****•:
*****************************
*********************
keymausl
FC2D04
7605
moveq . 1
#5, D3
Accept right button
FC2D06
08010004
btst
#4 , Dl
FC2D0A
6702
beq
$FC2D0E
is right button ($47/$C7)
FC2D0C
7606
moveq . 1
#6, D3
Left button
FC2D0E
08010007
btst
#7 , Dl
Pressed or released?
FC2D12
6706
beq
$FC2D1A
pressed
FC2D14
07AD0E1B
bclr
D3, $E1B(A5)
Clear bit for button
FC2D18
6004
bra
$FC2D1E
FC2D1A
O7ED0E1B
bset
D3,$E1B(A5)
Set bit for button
FC2D1E
7200
moveq . 1
#0, Dl
X to 0
FC2D20
7400
moveq . 1
#0, D2
Y to 0
***********************************
*********************
keymouse
FC2D22
41ED0E18
lea
$E18 ( A5) , A0
Pointer to mouse emulator buffer
FC2D26
246D0DDC
move . 1
$DDC(A5) , A2
Mouse interrupt vector
FC2D2A
4280
clr.l
DO
FC2D2C
102D0E1B
move . b
$E1B(A5) , DO
Get status of the "mouse" buttons
FC2D30
EA08
lsr.b
#5, DO
Bit for right/left to bits 0/1
Abacus Software Atari ST Internals
384
FC2D32
0 60000F8
add.b
#$F8 , DO
FC2D36
11400000
move . b
DO, (A0)
FC2D3A
11410001
move . b
Dl, 1 (A0)
FC2D3E
11420002
move .b
D2 , 2 (A0)
FC2D42
4E92
jsr
(A2)
FC2D44
2 05F
move . 1
(A7 ) + , A0
FC2D46
4E75
rts
***************************************************
FC2D48
47C752D2
dc .b
$47 , $C7, $52 , $D2
***************************************************
FC2D4C
302F0004
move . w
4 ( A7 ) , DO
FC2D50
322F0006
move . w
6 ( A7 ) , Dl
FC2D54
4 0E7
move .w
SR, -(hi)
FC2D56
007C0700
or .w
#$700, SR
FC2D5A
48E76080
movem . 1
D1-D2/A0, - (A7)
FC2D5E
4 1F9FFFF8800
lea
$FFFF8800, A0
FC2D64
1401
move .b
Dl , D2
FC2D66
0201000F
and.b
#$F , Dl
FC2D6A
1081
move . b
Dl, (A0)
FC2D6C
E302
asl.b
#1 , D2
FC2D6E
6404
bcc
$FC2D74
FC2D70
11400002
move . b
DO, 2 (A0)
FC2D74
7000
moveq . 1
#0, DO
FC2D76
1010
move . b
(A0) , DO
FC2D78
4CDF0106
movem . 1
(A7 ) +, D1-D2/A0
FC2D7C
4 6DF
move . w
(A7 ) +, SR
FC2D7E
4E75
rts
plus relative mouse header
in buffer
Store X-value
Store Y-value
Call mouse interrupt routine
iorec for keyboard back
mousekeyl
Scancode for pseudo mouse
giaccess, read write sound chip
Data
Register number plus read/write
Save status
IPL 7, disable interrupts
Save registers
Address of the sound chip
Get register number
Registers 0-15
Select register
Test read/write bit
Read
Write data byte in sound chip register
Read byte from sound chip
Restore registers
Restore status
Abacus Software Atari ST Internals
FC2D80 7408
FC2D82 6012
moveq.l #8,D2
bra $FC2D96
FC2D84 74F7
FC2D86 6034
moveq.l #$F7,D2
bra $FC2DBC
FC2D88 7410
FC2D8A 600A
moveq.l #$10, D2
bra $FC2D96
FC2D8C 74EF
FC2D8E 602C
moveq.l #$EF,D2
bra $FC2DBC
FC2D90 7400
FC2D92 342F0004
FC2D96 48E7E000
FC2D9A 40E7
FC2D9C 007C0700
FC2DA0 720E
FC2DA2 2F02
FC2DA4 61AE
FC2DA6 241F
FC2DA8 8002
FC2DAA 728E
FC2DAC 61A6
FC2DAE 4 6DF
FC2DB0 4CDF0007
FC2DB4 4E75
moveq.l #0,D2
move.w 4 (A7) ,D2
movem.l D0-D2,-(A7)
move.w SR, — ( A7 )
or.w #$700, SR
moveq.l #$E,D1
move.l D2,-(A7)
bsr $FC2D54
move.l (A7)+,D2
or.b D2,D0
moveq.l #$8E,D1
bsr $FC2D54
move.w (A7) +,SR
movem.l (A7)+,D0-D2
rtsoff, turn RTS off
Bit 3
Set in port A
rtson, turn RTS on
Bit 3
Clear in port A
dtroff, turn DTR off
Bit 4
Set in port A
dtron, turn DTR on
Bit 4
Clear in port A
ongibit, set bit(s) in sound chip port A
Get bit pattern
Save registers
Save status
IPL 7, disable interrupts
Read port A
Save bit pattern
Read port A
Restore bit pattern
OR bits to old value
Write port A
Write new value
Restore status
Restore registers
Abacus Software Atari ST Intern ;i
386
offgibit, clear bits in sound chip port A
FC2DB6
7400
moveq . 1
#0, D2
FC2DB8
342F0004
move . w
4 ( A7 ) ,D2
Bit pattern
FC2DBC
48E7E000
movem . 1
D0-D2 , - ( A7 )
Save registers
FC2DC0
4 0E7
move . w
SR, - (A7 )
Save status
FC2DC2
007C0700
or .w
#$700, SR
IPL 7, disable interrupts
FC2DC6
720E
moveq . 1
#$E,D1
Read port A
FC2DC8
2F02
move . 1
D2,-(A7)
Save bit pattern
FC2DCA
6188
bsr
$FC2D54
Read port A
FC2DCC
241F
move . 1
(A7 ) +,D2
Restore bit pattern
FC2DCE
C002
and. b
D2 , DO
Clear bits
FC2DD0
728E
moveq . 1
#$8E,D1
Write to port A
FC2DD2
6180
bsr
$FC2D54
Write new value
FC2DD4
46DF
move . w
(A7 ) +, SR
Restore status
FC2DD6
4CDF0007
movem . 1
(A7 ) +, D0-D2
Restore registers
FC2DDA
4E75
rts
********************************************************
initmouse
FC2DDC
4A6F0004
tst . w
4 (A7 )
Turn mouse off?
FC2DE0
6726
beq
$FC2E08
Yes, disable mouse
FC2DE2
2B6F000A0DDC
move . 1
10 ( A7 ) ,$DDC(A5)
Mouse interrpt vector
FC2DE8
2 66F000 6
move . 1
6 (A7 ) , A3
Address of the parameter block
FC2DEC
OC6F00010004
cmp.w
#1,4 (A7)
Relative mouse ?
FC2DF2
6724
beq
$FC2E18
Yes
FC2DF4
0C6F00020004
cmp . w
#2,4 (A7)
Absolute mouse ?
FC2DFA
6736
beq
$FC2E32
Yes
FC2DFC
0C6F00040004
cmp.w
#4,4 (A7)
Keycode mouse ?
FC2E02
6770
beq
$FC2E74
Yes
FC2E04
7000
moveq . 1
#0, DO
Error, invalid
FC2E06
4E75
rts
Abacus Software Atari ST Internals
387
FC2E08
7212
moveq . 1
#$12, D1
FC2E0A
6100F19C
bsr
5FC1FA8
FC2E0E
2B7C00FC2EDC0DDC
move . 1
#$FC2EDC, $DDC
FC2E16
6070
bra
$FC2E88
***********,*************************************.
FC2E18
45ED0E28
lea
$E28 (A5) , A2
FC2E1C
14FC0008
move . b
#8, <A2)+
FC2E20
14FC000B
move . b
#$B, (A2) +
FC2E24
6166
bsr
$FC2E8C
FC2E26
7606
moveq . 1
#6, D3
FC2E28
45ED0E28
lea
$E2 8 (A5) , A2
FC2E2C
6100F19A
bsr
$FC1FC8
FC2E30
6056
bra
$FC2E88
**************************************************
FC2E32
45ED0E28
lea
$E28 (A5) , A2
FC2E36
14FC0009
move . b
#9, (A2)+
FC2E3A
14EB0004
move . b
4 (A3) , (A2 ) +
FC2E3E
14EB0005
move . b
5 (A3) , (A2 ) +
FC2E42
14EB0006
move . b
6 (A3) , (A2 ) +
FC2E46
14EB0007
move . b
7 (A3) , <A2)+
FC2E4A
14FC000C
move . b
#$C , (A2) +
FC2E4E
613C
bsr
$FC2E8C
FC2E50
14FC000E
move . b
#$E, (A2) +
FC2E54
14FC0000
move . b
#0, ( A2 ) +
FC2E58
14EB0008
move . b
8 (A3) , ( A2 ) +
FC2E5C
14EB0009
move . b
9 (A3) , <A2)+
FC2E60
14EB000A
move . b
10 (A3) , (A2) +
FC2E64
14EB000B
move . b
11 (A3) , (A2) +
FC2E68
7610
moveq . 1
#16, D3
disable mouse
Disable mouse command
Send to IKBD
Mouse interrpt vector to rts
relative mouse
Transfer buffer pointer
Relative mouse
Relative mouse threshold x, y
Set mouse parameters
Length of string - 1
Transfer buffer pointer
Send string to IKBD
absolute mouse
Transfer buffer pointer
Absolute mouse
xmax msb
xmax lsb
ymax msb
ymax lsb
Absolute mouse scale
Set mouse parameters
Initial absolute mouse position
Fill byte
Start position x msb
Start position x lsb
Start position y msb
Start position y lsb
String length - 1
Abacus Software Atari ST Intern
FC2E6A 45ED0E28
FC2E6E 61 00F158
FC2E72 6014
lea
bsr
bra
$E28 (A5) , A2
$FC1FC8
$FC2E88
***************************
FC2E74 45ED0E28
FC2E78 14FC000A
FC2E7C 610E
FC2E7E 7605
FC2E80 45ED0E28
FC2E84 6100F142
FC2E88 70FF
FC2E8A 4E75
■**■*********★*★★★★***★*★★****
lea $E28(A5),A2
move.b #$A, (A2) +
bsr $FC2E8C
moveq.l #5,D3
lea $E28(A5),A2
bsr $FC1FC8
moveq.l #-l,D0
rts
U>
oo
oo
*★***★★■*'*★*★********★*****•**★*★*****★*★★*★★*★***'**★**★**
FC2E8C 14EB0002 move.b 2(A3),(A2)+
FC2E90 14EB0003 move.b 3(A3),(A2)+
FC2E94 7210 moveq.l #16, D1
FC2E96 922B0000 sub.b (A3),D1
FC2E9A 14C1 move.b Dl, (A2)+
FC2E9C 14FC0007 move.b #7,(A2)+
FC2EA0 14EB0001 move.b 1(A3),(A2)+
FC2EA4 4E75 rts
FC2EA6 7000
FC2EA8 7200
FC2EAA 7400
FC2EAC 302F0004
FC2EB0 322F0006
FC2EB4 342F0008
FC2EB8 6100F4AC
moveq.l #0,D0
moveq.l #0,D1
moveq.l #0,D2
move . w 4 ( A7 ) , DO
move ,w 6 (A7 ) , Dl
move . w 8 (A7 ) , D2
bsr $FC2366
Transfer buffer pointer
Send string to IKBD
Keycode mouse
Transfer buffer pointer
Mouse keycode mode
Set mouse parameters
Length of string - 1
Transfer buffer pointer
Send string to IKBD
Flag for OK
setmouse, set mouse parameters
x threshold, scale, delta
y threshold, scale, delta
top/bottom ?
xbtimer, initialize timer
Clear registers
Timer number (0-3 => A-D)
Value for control register
Value for date register
Set timer values
Abacus Software Atari ST Internals
u>
oo
vO
FC2EBC 4 AAF000A
FC2EC0 6B1 A
FC2EC2 2 4 6F000A
FC2EC6 7200
FC2EC8 43F900FC2EDE
FC2ECE 0280000000FF
FC2ED4 10310000
FC2ED8 6100F542
FC2EDC 4E75
tst.l 10 ( A7 )
bmi $FC2EDC
move . 1 10(A7),A2
moveq.l #0,D1
lea $FC2EDE,A1
and. 1 #$FF , DO
move.b 0 ( A1 , DO . w) , DO
bsr $FC2 4 1C
rts
FC2EDE 0D0805O4 dc.b 13,8,5,4
FC2EE2
4AAF0004
tst.l
4 ( A7 )
FC2EE6
6B0 6
bmi
$FC2EEE
FC2EE8
2B6F00040E1C
move . 1
4 ( A7 ) ,$E1C(A5)
FC2EEE
4AAF0008
tst.l
8 ( A7 )
FC2EF2
6B0 6
bmi
$FC2EFA
FC2EF4
2B6F00080E20
move . 1
8<A7) , $E20 ( A5)
FC2EFA
4AAF00OC
tst.l
12 ( A7 )
FC2EFE
6B0 6
bmi
$FC2F06
FC2F00
2B6F000C0E24
move . 1
12 (A7) , $E2 4 (A5)
FC2F06
2 03COOOOOE1C
move . 1
#$E1C, DO
FC2F0C
4E75
rts
********************************************************
FC2F0E 2B7COOFC2034OE1C move . 1 #$FC2034 , $E1C (A5)
FC2F16 2B7C0QFC20B40E20 move . 1 #$FC20B4 , $E20 (A5)
FC2F1E 2B7C00FC21340E24 move . 1 #$FC2134, $E24 (A5)
FC2F26 4E75
rts
Corresponding interrupt vector
not used?
Get vector
Table for determining interrupt number
Get interrupt number
initint, install interrupt
Interrupt numbers of the MFP timer
keytrans, set keyboard tables
Change standard table?
No
Address of the standard table
Change shift table?
No
Address of the shift table
Change Caps Lock table
No
Address of the Caps Lock table
Pointer to addresses of the tables
bioskeys, standard keyboard table
Standard table
Shift table
Caps Lock table
Abacus Software Atari ST Internals
390
FC2F28
202D0E44
move . 1
$E4 4 (A5) , DO
FC2F2C
222F0004
move . 1
4 (A7 ) , D1
FC2F30
6B08
bmi
$FC2F3A
FC2F32
2B410E44
move . 1
Dl, $E44 (A5)
FC2F36
422D0E48
clr . b
$E4 8 ( A5)
FC2F3A
4E75
rts
*************************************,************
FC2F3C
302D0E4A
move . w
$E4A(A5) , DO
FC2F40
4 A6F0004
tst . w
4 (A7 )
FC2F44
6B0 6
bmi
$FC2F4C
FC2F46
3B6F0004 0E4 A
move . w
4 (A7 ) ,$E4A(A5)
FC2F4C
4E75
rts
**************************************************.
FC2F4E
302D0E3C
move . w
$E3C(A5) , DO
FC2F52
4 A6F0004
tst .w
4 ( A7 )
FC2F56
6B1 6
bmi
$FC2F6E
FC2F58
322F0004
move . w
4 (A7 ) , Dl
FC2F5C
1B410E3C
move . b
Dl, $E3C (A5)
FC2F60
4A6F000 6
tst .w
6 ( A7 )
FC2F64
6B08
bmi
$FC2F6E
FC2F66
322F0006
move . w
6 (A7 ) , Dl
FC2F6A
1B410E3D
move . b
Dl, $E3D (A5)
FC2F6E
4E75
rts
*★★**★***★**★****★★★*★★***★*★■*•★**★★*★★*★★★★***★★★**★★★★★
FC2F70 203C0O000DCC move . 1 #$DCC,D0
FC2F76 4E75 rts
dosound, start sound
Get sound status
Address of the sound table
Don't set
New sound table
Start sound timer
setprt, set/get printer configuration
Old printer configuration
New value negative?
Yes, don't set
Set new value
kbrate, set/get keyboard repeat
Delay before key repeat
new value negative?
Yes, don't set
Get new value
and save
Repeat rate
Negative, don't set
Get new value
and save
ikbdvecs, pointer to IKBD + MIDI vectors
Address of the vector table
Abacus Software Atari ST Internals
FC2F78 52 B90 000 04 BA
FC2F7E E7F900000E42
FC2F84 6A4E
FC2F86 48E7FFFE
FC2F8A 4BF900000000
FC2F90 614C
FC2F92 082D00010484
FC2F98 672A
FC2F9A 4A2D0E39
FC2F9E 6724
FC2FA0 4 A2D0E3A
FC2FA4 6706
FC2FA6 532D0E3A
FC2FAA 6618
FC2FAC 532D0E3B
FC2FB0 6612
1-4 FC2FB2 1B6D0E3D0E3B
FC2FB8 102D0E39
FC2FBC 4 1ED0DB0
FC2FC0 6100FACE
FC2FC4 3F2D0442
FC2FC8 206D0400
FC2FCC 4E90
FC2FCE 544F
FC2FD0 4CDF7FFF
FC2FD4 08B90005FFFFFA11
FC2FDC 4E73
*************************
FC2FDE 48E7C080
FC2FE2 2 02D0E4 4
addq .1 #1 , $4BA
rol.w $E42
bpl $FC2FD4
movem.l D0-D7/A0-A6, - (A7)
lea $0,A5
bsr $FC2FDE
btst #1, $484 (A5)
beq 5FC2FC4
tst.b $E39(A5)
beq $FC2FC4
tst.b $E3A(A5)
beq $FC2FAC
subq.b #1,$E3A(A5)
bne $FC2FC4
subq.b #1,$E3B(A5)
bne $FC2FC4
move . b $E3D (A5) , $E3B(A5)
move.b $E39(A5),D0
lea $DB0 ( A5) , AO
bsr $FC2A90
move.w $442 (A5) , - (A7)
move.l $400(A5),A0
jsr (A0)
addq.w #2,A7
movem.l ( A7 ) +, DO-D7/AO-A6
bclr #5, $FFFFFA11
rte
*******************************
movem.l D0-D1/A0, - (A7)
move.l $E44(A5),D0
timercint, timer C interrupt
hz_200, increment 200 Hz counter
Rotate bit map
Not fourth interrupt, then done
Save registers
Clear A5
Process sound
conterm, key repeat enabled ?
No
Key pressed ?
No
Counter for start delay
Not active
decrement counter
Not run out?
Decrement counter for repeat rate
Not run out?
Reload counter
Key to repeat
Pointer to iorec keyboard
Key code in keyboard buffer
_timer_ms
etv_timer
Execute routine
Correct stack pointer
Restore register
Clear interrupt service bit
sndirq, sound interrupt routine
Save registers
Pointer to sound table
Abacus Software Atari ST Internals
392
r
FC2FE6
67000088
beq
SFC3070
No sound active?
FC2FEA
2040
move . 1
DO, A0
Pointer to A0
FC2FEC
102D0E48
move . b
$E48 (A5) , DO
Load timer value
FC2FF0
6708
beq
$FC2FFA
New sound started?
FC2FF2
5300
subq . b
#1 , DO
Else decrement timer
FC2FF4
1B400E48
move . b
DO, $E48 (A5)
and store again
FC2FF8
6076
bra
$FC3070
Done
FC2FFA
1018
move .b
(A0) +, DO
Get sound command
FC2FFC
6B2E
bmi
$FC302C
Bit 7 set, special command
FC2FFE
13C0FFFF8800
move . b
DO, $FFFF8800
Select register in sound chip
FC3004
0C000007
cmp.b
#7, DO
Mixer ?
FC3008
661A
bne
$FC3024
No
FC300A
1218
move . b
(A0) +,D1
Data for mixer
FC300C
0201003F
and.b
#$3F,D1
Isolate bits 0-5
FC3010
1039FFFF8800
move . b
$FFFF8800 , DO
Read mixer
FC3016
020000C0
and.b
#$C0, DO
Isolate bits 6-7
FC301A
8001
or .b
Dl, DO
OR with sound data
FC301C
13C0FFFF8802
move . b
DO, $FFFF8802
and write in register
FC3022
60D6
bra
$FC2FFA
Next sound command
FC3024
13D8FFFF8802
move . b
(A0) +, $FFFF8802
Write byte directly in sound chip
FC302A
60CE
bra
$FC2FFA
Next sound command
FC302C
5200
addq . b
#1 , DO
Was command $FF ?
FC302E
6A32
bpl
$FC3062
Yes
FC3030
0C000081
cmp . b
#$81, DO
Was command $80 ?
FC3034
6606
bne
$FC303C
No
FC3036
1B580E4 9
move . b
(AO) +, $E4 9 ( A5)
Save byte for later
FC303A
60BE
bra
$FC2FFA
Next sound command
FC303C
0C000082
cmp . b
#$82, DO
Was command $81 ?
FC3040
6620
bne
$FC3062
No
FC3042
13D8FFFF8800
move . b
(A0) +, $FFFF8800
Select register
FC3048
1018
move . b
(A0) +, DO
Increment value
FC304A
D12D0E4 9
add.b
DO, $E4 9 (A5)
Add
Abacus Software Atari ST Internals
FC304E 1018
FC3050 13ED0E49FFFF8802
FC3058 B02D0E49
FC305C 670E
FC305E 5948
FC3060 600A
FC3062 1B580E48
FC3066 6604
FC3068 307COOOO
FC306C 2B480E44
FC3070 4CDF0103
FC3074 4E75
move . b (AO ) +, DO
move . b $E4 9 (A5) , $FFFF8802
cmp.b $E4 9 ( A5) , DO
beq $FC306C
subq.w #4, AO
bra $FC306C
move.b (AO) +, $E48 (A5)
bne 5FC306C
move.w #0,A0
move . 1 A0,$E44(A5)
movem.l (A7) +, D0-D1/A0
rts
U>
SO
U>
FC3076
0034
dc .b
0, $34
FC3078
0100
dc .b
1,0
FC307A
0200
dc.b
2,0
FC307C
0300
dc.b
3,0
FC307E
0400
dc.b
4,0
FC3080
0500
dc.b
5,0
FC3082
0600
dc.b
6,0
FC3084
07FE
dc.b
7 , $FE
FC3086
0810
dc.b
8, 10
FC3088
0900
dc.b
9,0
FC308A
0A00
dc.b
10, 0
FC308C
0B00
dc.b
11,0
FC308E
OCIO
dc.b
12,16
FC3090
OD09
dc.b
13, 9
FC3092
FFOO
dc.b
$FF, 0
End value
Write temp value in sound chip
End value reached?
Yes
Sound back to same command
Next value as delay timer
Clear sound pointer
Save current sound pointer
Restore registers
bellsnd, sound for CTRL G
Abacus Software Atari ST Internals
394
r
keyclick, sound on key click
FC3094
003B
dc .b
0, $3B
FC3096
0100
dc .b
1,0
FC3098
0200
dc . b
2,0
FC309A
0300
dc .b
3, 0
FC309C
0400
dc .b
4,0
FC309E
0500
dc .b
5, 0
FC30A0
0600
dc .b
6,0
FC30A2
07FE
dc .b
7, $FE
FC30A4
0810
dc .b
8,16
FC30A6
0D03
dc .b
13,3
FC30A8
0B80
dc .b
11, $80
FC30AA
0C01
dc .b
12,1
FC30AC
FF00
dc .b
$FF, 0
*★******★★**★★■*****★■*■**
*********************************
prtblk, hardcopy
FC30AE
4E560000
link
A6, tO
FC30B2
48E7070C
movem. 1
D5-D7/A4-A5 , - (A7 )
Save registers
FC30B6
2A6E0008
move . 1
8 (A6) , A5
Address of the parameter block
FC30BA
287C000029BE
move . 1
#$2 9BE, A4
Address of the working memory
FC30C0
7E1E
moveq. 1
#30, D7
30 bytes
FC30C2
6004
bra
$FC30C8
FC30C4
18DD
move . b
<A5)+, (A4 ) +
Copy parameters in working memory
FC30C6
5347
subq . w
#1 , D7
FC30C8
4A4 7
tst . w
D7
FC30CA
6EF8
bgt
$FC30C4
Next byte
FC30CC
0C790001000029D6
cmp.w
#1, $29D6
p_port
FC30D4
630E
bis
$FC30E4
0 or 1 ?
FC30D6
33FCFFFF000004EE
move . w
#-l, $4EE
Clear dumpflg
FC30DE
7 OFF
moveq . 1
#-l, DO
Flag for error
FC30E0
60000F6C
bra
$FC404E
Terminate
Abacus Software Atari ST Internals
FC30E4 4 A7 900002 9D6
tst . w
$2 9D 6
p port
FC30EA 6704
beq
$FC30F0
Centronics ?
FC30EC 4240
clr . w
DO
0 = RS 232
FC30EE 6002
bra
$FC30F2
FC30F0 7001
moveq . 1
#1 , DO
1 = Centronics
FC30F2 13C000002 9BC
move . b
DO, $29BC
Save printer port
FC30F8 4A7 900002 9C6
tst . w
$2 9C6
p height
FC30FE 6654
bne
$FC3154
Not zero?
FC3100 6032
bra
$FC3134
Else just dump p width bytes
FC3102 OC790001000004EE
cmp . w
#1 , $4EE
dumpflg to one?
FC310A 663A
bne
$FC3146
Terminate hardcopy?
FC310C 207 900002 9BE
move . 1
$29BE, A0
p blkptr, screen address
FC3112 1010
move . b
(A0) , DO
Get byte
FC3114 4880
ext .w
DO
FC3116 3E80
move . w
DO, ( A7 )
on the stack
LO
vO
FC3118 61000F3E
bsr
$FC4058
Output character
Ul
FC311C 52B900002 9BE
addq . 1
#1, $29BE
Increment p_blkptr
FC3122 4A40
tst .w
DO
Output OK ?
FC3124 67 OE
beq
$FC3134
Yes
FC3126 33FCFFFF000004EE
move . w
#-l, $4EE
Clear dumpflg
FC312E 70FF
moveq. 1
#-l , DO
Flag for error
FC3130 60000F1C
bra
$FC404E
Terminate
FC3134 4240
clr .w
DO
FC3136 3039000029C4
move . w
$2 9C4 , DO
p width
FC313C 537 900002 9C4
subq . w
#1, $29C4
Decrement p width
FC3142 4A4 0
tst . w
DO
Not zero yet?
FC3144 66BC
bne
$FC3102
Output next character
FC3146 33FCFFFF000004EE
move . w
#-l, $4EE
Clear dumpflg
FC314E 4240
clr .w
DO
OK
FC3150 60000EFC
bra
$FC404E
Terminate
A
Abacus Software Atari ST Internals
396
FC3154
0C7 9000300002 9D 4
cmp . w
#3, $2904
FC315C
630E
bis
$FC3 1 6C
FC315E
33FCFFFF000004EE
move . w
#-l, $4 EE
FC3166
7 0FF
moveq . 1
#-l , DO
FC3168
60000EE4
bra
$FC4 04E
FC316C
0C7 9000 100002 9CE
cmp . w
#1, $29CE
FC3174
630E
bis
$FC3184
FC3176
33FCFFFF000004EE
move . w
#-l, $4EE
FC317E
70FF
moveq . 1
#-l, DO
FC3180
60000ECC
bra
$FC404E
FC3184
0C7 90002 00002 9CC
cmp.w
#2 , $2 9CC
FC318C
630E
bis
$FC319C
FC318E
33FCFFFF000004EE
move . w
#-l, $4EE
FC3196
70FF
moveq. 1
#-l , DO
FC3198
60000EB4
bra
$FC404E
FC319C
0C7 90007 00 002 9C2
cmp . w
#7 , $2 9C2
FC31A4
630E
bis
$FC31B4
FC31A6
33FCFFFF000004EE
move . w
#-l, $4EE
FC31AE
70FF
moveq . 1
#-l, DO
FC31B0
60000E9C
bra
$FC404E
FC31B4
4A79000029CC
tst . w
$2 9CC
FC31BA
6704
beq
$FC31C0
FC31BC
4240
clr . w
DO
FC31BE
6002
bra
$FC31C2
FC31C0
7001
moveq . 1
#1 , DO
FC31C2
13C00000609A
move . b
DO, $609A
FC31C8
0C7 9000 100002 9CC
cmp.w
#1 , $2 9CC
FC31D0
6704
beq
$FC31D6
p_type
OK ?
Clear _dumpflg
Flag for error
Terminate
p_destres, printer resolution
OK ?
Clear _dumpflg
Flag for error
Terminate
p_srcres, screen resolution
OK ?
Clear _dumpflg
Flag for error
Terminate
p_of f set
OK ?
Clear _dumpflg
Flag for error
Terminate
p_srcres, screen resolution
Low resolution ?
Flag for low resolution
p_srcres, screen resolution
Medium resolution ?
Abacus Software Atari ST Internals
FC31D2
4240
clr .w
DO
FC31D4
6002
bra
5FC31D8
FC31D6
7001
moveq . 1
#1, DO
FC31D8
13C000005FE4
move . b
DO, $5FE4
FC31DE
0C7 90002 00 002 9CC
cmp . w
#2 , $2 9CC
FC31E6
6704
beq
$FC31EC
FC31E8
4240
clr .w
DO
FC31EA
6002
bra
$FC31EE
FC31EC
7001
moveq . 1
#1 , DO
FC31EE
13C000005FE6
move . b
DO, $5FE6
FC31F4
4A7 900002 9CE
tst .w
$2 9CE
FC31FA
6704
beq
$FC3200
FC31FC
4240
clr .w
DO
FC31FE
6002
bra
$FC3202
FC3200
7001
moveq. 1
#1 , DO
FC3202
13C000005FFE
move . b
DO, S5FFE
FC3208
0C7 9000100 002 9D4
cmp.w
#1 , $2 9D4
FC3210
6704
beq
$FC32 1 6
FC3212
4240
clr .w
DO
FC3214
6002
bra
$FC3218
FC3216
7001
moveq. 1
#1 , DO
FC3218
13C00000575E
move .b
DO, $575E
FC321E
0C7 90002 00002 9D4
cmp . w
#2 , $2 9D4
FC3226
6704
beq
$FC322C
FC3228
4240
clr .w
DO
FC322A
6002
bra
$FC322E
FC322C
7001
moveq . 1
#1 , DO
FC322E
13C00000609C
move . b
DO, $609C
FC3234
0C7 9000300002 9D4
cmp.w
#3 , $2 9D4
FC323C
6704
beq
$FC3242
FC323E
4240
clr .w
DO
FC3240
6002
bra
$FC32 4 4
Flag for medium resolution
p srcres, screen resolution
High resolution ?
Flag for high resolution
p destres, printer resolution
Test mode?
Quality mode
Flag for mode
p_type, ATARI color dot-matrix printer?
Flag for ATARI color dot-matrix printer
p_type, ATARI daisy-wheel printer?
Flag for ATARI daisy-wheel printer
p type, Epson B/W dot-matrix printer?
Yes
Else ATARI B/W matrix printer
Abacus Software Atari ST Internals
398
r
FC3242
7001
moveq . 1
#1 , DO
FC3244
13C000005780
move . b
DO, $5780
FC324A
4A390000609C
tst . b
$60 9C
FC3250
67 0E
beq
$FC3260
FC3252
33FCFFFF000004EE
move . w
#-l, $4EE
FC325A
7 OFF
moveq . 1
#-l , DO
FC325C
60000DFO
bra
$FC4 04E
FC3260
4A3900005780
tst . b
$5780
FC3266
670C
beq
$FC3274
FC3268
4A3 900005FFE
tst .b
$5FFE
FC326E
6604
bne
$FC3274
FC3270
7001
moveq . 1
o
Q
rH
FC3272
6008
bra
$FC327C
FC3274
103900005FFE
move.b
$5FFE, DO
FC327A
4880
ext .w
DO
FC327C
13C000005FFE
move . b
DO, $5FFE
FC3282
4A390000609A
tst .b
$60 9A
FC3288
6726
beq
$FC32B0
FC328A
0C790140000029C4
cmp . w
#320, $29C4
FC3292
631C
bis
$FC32B0
FC3294
4240
clr . w
DO
FC3296
3039000029C4
move . w
$2 9C4 , DO
FC329C
D07CFECO
add . w
#-320, DO
FC32A0
D179000029CA
add.w
DO, $2 9CA
FC32A6
33 FC 014 000002 9C 4
move . w
#320, $29C4
FC32AE
6024
bra
$FC32D4
FC32B0
0C7 902 8000002 9C 4
cmp . w
#640, $29C4
FC32B8
631A
bis
$FC32D4
FC32BA
4240
clr . w
DO
FC32BC
3039000029C4
move . w
$2 9C4 , DO
FC32C2
D07CFD80
add.w
#-640, DO
Flag for Epson B/W dot matrix printer
ATARI daisy wheel?
No
Clear _dumpflg
Flag for error
Terminate
Epson B/W dot-matrix?
No
Quality mode?
No
Quality mode
Quality mode
Low resolution ?
No
p_width
p_width
p_right
p_width
p_width
p_width
399
FC32C6
D17 900002 9CA
add. w
DO, $2 9CA
p right
FC32CC
33FC0280000029C4
move . w
#640, $29C4
p width
FC32D4
4 AB900002 9D8
t st . 1
$2 9D8
p masks, half-tone mask
FC32DA
6614
bne
$FC32F0
FC32DC
2 3FC00FD1BAC00002 9D8
move . 1
#$FD1BAC, $29D8
Use default mask
FC32E6
13FC000100004DBA
move . b
#1 , $4DBA
FC32EE
6006
bra
$FC32F6
FC32F0
423900004DBA
clr .b
$4DBA
FC32F6
4A3900005FE6
tst ,b
$5FE6
High resolution ?
FC32FC
6718
beq
$FC3316
No
FC32FE
2079000029D0
move . 1
$29D0, A0
p colpal
FC3304
4240
clr .w
DO
FC3306
3010
move . w
(A0) , DO
Get color
FC3308
C07C0001
and.w
#1 , DO
FC330C
33C00000608C
move . w
DO, $608C
FC3312
60000290
bra
$FC35A4
FC3316
4247
clr .w
D7
Clear counter for running
color
FC3318
60000282
bra
$FC359C
To loop end
FC331C
207 900002 9D0
move . 1
$2 9D0, A0
colpal, address of color
palette
FC3322
4240
clr ,w
DO
FC3324
3010
move . w
(A0) , DO
Get color
FC3326
C07C0777
and.w
#$777, DO
Mask irrelevant bits
FC332A
33C00000574A
move . w
DO, $574A
Mask color
FC3330
54B900002 9D0
addq . 1
#2 , $2 9D0
Poiner to next color
FC3336
0C7 9077 7 000057 4A
cmp.w
#$777 , $574 A
Color equals white?
FC333E
67000230
beq
$FC3570
Yes
FC3342
3039000057 4A
move . w
$574A, DO
Load color
FC3348
C07C0007
and.w
#7, DO
Isolate blue level
FC334C
33C000004150
move .w
DO, $4150
And save
FC3352
30390000574A
move .w
$57 4A, DO
Load color
FC3358
E84 0
asr .w
#4, DO
d
Abacus Software Atari ST Internals
400
r
FC335A C07C0007
FC335E 33C000005FE8
FC3364 30390000574A
FC336A E040
FC336C C07C0007
FC3370 33C000005624
FC3376 4A390000575E
FC337C 670001A0
FC3380 3047
FC3382 D1C8
FC338 4 D1FC000057 60
FC338A 30B900005624
FC3390 3047
FC3392 D1C8
FC3394 227C000057 60
FC339A 30309800
FC339E B07 900005FE8
FC33A4 6C08
FC33A6 303900005FE8
FC33AC 600E
FC33AE 3047
FC33B0 D1C8
FC33B2 22 7C0 00057 60
FC33B8 30309800
FC33BC 3247
FC33BE D3C9
FC33C0 D3FC000057 60
FC33C6 3280
FC33C8 3047
FC33CA D1C8
FC33CC 227C000057 60
FC33D2 30309800
and. w
#7, DO
move . w
DO, $5FE8
move . w
$574 A, DO
asr . w
#8, DO
and. w
#7, DO
move . w
DO, $5624
tst .b
$575E
beq
$FC351E
move . w
D7 , A0
add. 1
A0, A0
add. 1
#$5760, A0
move . w
$5624, (A0)
move . w
D7 , A0
add. 1
A0, A0
move . 1
#$5760, A1
move . w
0 (A0, A1 . 1) , DO
cmp. w
$5FE8, DO
bge
$FC33AE
move . w
$5FE8, DO
bra
$FC33BC
move . w
D7 , A0
add. 1
A0, A0
move . 1
#$5760, A1
move . w
0 (A0, Al.l) , DO
move . w
D7,A1
add. 1
A1,A1
add. 1
#$5760, A1
move . w
DO, (Al)
move . w
D7, A0
add. 1
A0, A0
move . 1
#$5760, Al
move . w
0 (A0, Al.l) , DO
Isolate green level
and save
Load color
Isolate red level
and save
ATARI color dot-matrix printer?
No
Red level
Green level
Green level
Abacus Software Atari ST Internals
4^
O
FC33D6 BO 7 900004 150
FC33DC 6C08
FC33DE 303900004150
FC33E4 600E
FC33E6 3047
FC33E8 D1C8
FC33EA 22 7C000057 60
FC33F0 30309800
FC33F4 3247
FC33F6 D3C9
FC33F8 D3FC000057 60
FC33FE 3280
FC3400 3047
FC3402 D1C8
FC3404 D1FC000057 60
FC340A 5250
FC340C 3047
FC340E D1C8
FC3410 D1FC00006002
FC3416 30B900005624
FC341C 3047
FC341E D1C8
FC3420 227C00006002
FC3426 30309800
FC34 2A B07 900005FE8
FC3430 6F08
FC3432 303900005FE8
FC3438 600E
FC343A 3047
FC343C D1C8
FC343E 227C00006002
FC3444 30309800
cmp.w $4150, DO
bge $FC33E6
move . w $4150, DO
bra $FC33F 4
move.w D7,A0
add.l AO, AO
move.l #$5760, A1
move.w 0 ( A0 , A1 . 1) , DO
move.w D7,A1
add.l A1,A1
add.l #$5760, A1
move . w DO , ( A1 )
move.w D7,A0
add.l A0, A0
add.l #$5760, A0
addq.w #1, (A0)
move.w D7,A0
add.l A0, A0
add.l #$6002, AO
move.w $5624, (AO)
move.w D7,A0
add.l AO, AO
move.l #$6002,A1
move.w 0 (AO, A1 . 1) , DO
cmp.w $5FE8,D0
ble $FC343A
move.w $5FE8,D0
bra $FC34 4 8
move . w D7 , A0
add.l AO, AO
move.l #$6002, A1
move.w 0 ( AO , A1 . 1) , DO
Blue level
Blue level
Red level
Green level
Green level
Abacus Software Atari ST Internals
402
r
FC3448
3247
move . w
D7,A1
FC344A
D3C9
add . 1
A1,A1
FC344C
D3FC00006002
add. 1
#$6002, A1
FC3452
3280
move . w
DO, <A1)
FC3454
3047
move . w
D7, A0
FC3456
D1C8
add. 1
A0, AO
FC3458
227C00006002
move . 1
#$6002, A1
FC345E
30309800
move . w
0 (A0 , A1 . 1 ) , DO
FC3462
B07 900004 150
cmp . w
$4150, DO
Green level
FC3468
6F08
ble
$FC3472
FC346A
303900004150
move . w
$4150, DO
Green level
FC3470
600E
bra
$FC3480
FC3472
3047
move . w
D7 , A0
FC3474
D1C8
add. 1
A0, A0
FC3476
227C00006002
move . 1
#$6002, A1
FC347C
30309800
move . w
0 (A0, A1 . 1) , DO
FC3480
3247
move . w
D7,A1
FC3482
D3C9
add. 1
A1,A1
FC3484
D3FC00006002
add. 1
#$6002, A1
FC348A
3280
move . w
DO, (Al)
FC348C
303900005624
move . w
$5624, DO
Red level
FC3492
3247
move . w
D7, Al
FC3494
D3C9
add. 1
Al, Al
FC3496
D3FC00006002
add. 1
#$6002, Al
FC349C
3211
move . w
(Al) ,D1
FC349E
5241
addq . w
#1 , D1
FC34A0
9041
sub . w
D1 , DO
FC34A2
6E04
bgt
$FC34A8
FC34A4
4240
clr .w
DO
FC34A6
6002
bra
$FC34 AA
FC34A8
7001
moveq . 1
#1 , DO
FC34AA
33C000005 62 4
move . w
DO, $5624
Red level
Abacus Software Atari ST Internals
403
FC34B0
FC34B6
FC34B8
FC34BA
FC34C0
FC34C2
FC34C4
FC34C6
FC34C8
FC34CA
FC34CC
FC34CE
FC34D4
FC34DA
FC34DC
FC34DE
FC34E4
FC34E6
FC34E8
FC34EA
FC34EC
FC34EE
FC34F0
FC34F2
FC34F8
FC34FE
FC3500
FC3506
FC3508
FC350A
FC3510
FC3512
303900005FE8
move . w
$5FE8 , DO
Green level
3247
move . w
D7,A1
D3C9
add. 1
A1,A1
D3FC00006002
add. 1
#$6002, A1
3211
move . w
(Al) , D1
5241
addq . w
#1 , D1
9041
sub.w
D1 , DO
6E04
bgt
$FC34CC
4240
clr .w
DO
6002
bra
$FC34CE
7001
moveq. 1
#1 , DO
33C000005FE8
move . w
DO, $5FE8
Green level
303900004150
move . w
$4150,00
Blue level
3247
move . w
D7, Al
D3C9
add. 1
Al, Al
D3FC00006002
add. 1
#$6002, Al
3211
move . w
(Al) ,D1
5241
addq . w
#1 , D1
9041
sub.w
Dl, DO
6E04
bgt
$FC34F0
4240
clr .w
DO
6002
bra
$FC34F2
7001
moveq . 1
#1 , DO
33C000004 150
move . w
DO, $4150
Blue level
303900005624
move . w
$5624, DO
Red level
E54 0
asl.w
#2, DO
times 4
323900005FE8
move . w
$5FE8, Dl
Green level
E341
asl.w
#1, Dl
times 2
D04 1
add.w
o
Q
rH
Q
Add to red level
D07900004150
add.w
$4150, DO
Add blue level
3247
move . w
D7, Al
D3C9
add. 1
Al , Al
A
Abacus Software Atari ST Internals
404
r
FC3514
D3FC00005628
add. 1
#$5628, A1
FC351A
3280
move . w
DO, (Al)
FC351C
6050
bra
$FC356E
FC351E
303900005624
move . w
$5624, DO
Red level
FC3524
C1FC001E
muls . w
#$1E, DO
times 30, weighting
30 %
FC3528
323900005FE8
move . w
$5FE8, D1
Green level
FC352E
C3FC003B
muls . w
#$3B,D1
times 59, weighting
59 %
FC3532
D04 1
add. w
Dl, DO
FC3534
323900004150
move . w
$4150, D1
Blue level
FC353A
C3FC000B
muls . w
#$B, Dl
times 11, weighting
11 %
FC353E
D04 1
add.w
Dl, DO
FC3540
4 8C0
ext . 1
DO
FC3542
81FC0064
divs . w
#$ 64 , DO
divided by 100, scaling
FC3546
3247
move . w
D7, Al
FC3548
D3C9
add. 1
Al, Al
FC354A
D3FC00006002
add. 1
#$6002, Al
FC3550
3280
move . w
DO, (Al)
FC3552
3047
move . w
D7, A0
FC3554
D1C8
add. 1
A0, A0
FC3556
D1FC00005628
add. 1
#$5628, A0
FC355C
30BC0007
move . w
#7, (A0)
FC3560
3047
move . w
D7, A0
FC3562
D1C8
add. 1
A0, A0
FC3564
D1FC 000057 60
add. 1
#$5760, A0
FC356A
30BC0008
move . w
#8, (A0)
FC356E
602A
bra
$FC359A
FC3570
3047
move . w
D7, A0
FC3572
D1C8
add. 1
AO, AO
FC3574
D1FC0000 6002
add. 1
#$6002, AO
FC357A
30BC0008
move . w
#8, (AO)
FC357E
30 47
move . w
D7, AO
FC3580
D1C8
add. 1
AO, AO
Abacus Software Atari ST Internals
405
FC3582
D1 FC00005 62 8
add. 1
#$5628, A0
FC3588
30BC0007
move . w
#7, (A0)
FC358C
3047
move . w
D7, A0
FC358E
D1C8
add . 1
A0, A0
FC3590
D1FC000057 60
add . 1
#$5760, A0
FC3596
30BC0008
move . w
#8, (A0)
FC359A
5247
addq . w
#1 , D7
FC359C
BE7C0010
cmp . w
#$10, D7
FC35A0
6D00FD7A
bit
$FC331C
FC35A4
4 A3 90000 60 9A
tst .b
$609A
FC35AA
6716
beq
$FC35C2
FC35AC
7004
moveq. 1
#4, DO
FC35AE
33C000006022
move . w
DO, $6022
FC35B4
33C000005FF8
move . w
DO, $5FF8
FC35BA
33C0000056F8
move . w
DO, $56F8
FC35C0
6038
bra
$FC35FA
FC35C2
4A3 900005FE4
tst .b
$5FE4
FC35C8
6718
beq
$FC35E2
FC35CA
7002
moveq . 1
#2, DO
FC35CC
33C000006022
move . w
DO, $6022
FC35D2
33C0000056F8
move . w
DO, $56F8
FC35D8
33FC000400005FF8
move . w
#4 , $5FF8
FC35E0
6018
bra
$FC35FA
FC35E2
33 FC 000 100005 6F8
move . w
#1, $56F8
FC35EA
33FC 000800005 FF 8
move . w
#8 , $5FF8
FC35F2
33FC 000200006022
move . w
#2, $6022
FC35FA
4A3 9000057 80
tst .b
$5780
FC3600
6706
beq
$FC3608
FC3602
3F3C0002
move . w
#2, - (A7)
FC3606
6004
bra
$FC360C
FC3608
3F3C0001
move . w
#1 , - (A7 )
FC360C
303900006022
move . w
$6022, DO
Next color
16 colors?
No, next color
Low resolution ?
No
Four points per screen point
Medium resolution ?
No
2 points per screen point
Epson B/W dot matrix printer?
No
Abacus Software Atari ST Internals
406
FC3612 4 8C0
FC3614 81DF
FC3616 33C000006022
FC361C 4240
FC361E 3039000029C8
FC3624 D07 900002 9C4
FC362A D07 9000029CA
FC3630 C0F9000056F8
FC3636 E84 8
FC3638 33C000005626
FC363E 303900005626
FC3644 C1F900005FF8
FC364A 33C000004E10
FC3650 2039000029BE
FC3656 COBCFFFFFFFE
FC365C 23C000005648
FC3662 2039000029BE
FC3668 BOB900005648
FC366E 660A
FC3670 4240
FC3 672 303 900002 9C2
FC3678 600A
FC367A 4240
FC367C 303 900002 9C2
FC3682 5040
FC3684 33C00000574C
FC368A 13FC0001000060AO
FC3692 42 7 900001 6A8
FC3698 60000976
FC369C 0C7 90001 00000 4EE
FC36A4 6600097C
FC36A8 4 A3900004DBA
ext.l DO
divs.w (A7) + , DO
move . w DO, $6022
clr.w DO
move . w $29C8, DO
add. w $2 9C4 , DO
add. w $2 9CA, DO
mulu.w $56F8,D0
lsr.w #4, DO
move . w DO, $5626
move . w $5626, DO
muls.w $5FF8, DO
move.w DO, $4E10
move . 1 $2 9BE, DO
and. 1 #$FFFFFFFE, DO
move . 1 DO, $5648
move . 1 $2 9BE, DO
cmp.l $5648, DO
bne $FC3 67A
clr.w DO
move.w $2 9C2 , DO
bra $FC3684
clr.w DO
move.w $2 9C2 , DO
addq.w #8, DO
move.w DO, $574C
move . b #1,$60A0
clr.w $1 6A8
bra $FC4010
cmp.w #1, $4EE
bne $FC4 022
tst.b $4 DBA
p_left
p__width
p_right
divided by 16
p_blkptr, screen address
Even address
save
p_blkptr
p_of fset
p_of f set
dumpflg at one?
Abacus Software Atari ST Internals
407
FC36AE
6700018E
beq
SFC383E
FC36B2
13FC0001000041B6
move . b
#1, $41B6
FC36BA
4240
clr . w
DO
FC36BC
303 900002 9C4
move . w
$2 9C4 , DO
FC36C2
C0F9000056F8
mulu . w
$56F8, DO
FC36C8
E848
lsr .w
#4, DO
FC36CA
907 900005 6F8
sub.w
$56F8, DO
FC36D0
E34 8
lsl.w
#1 , DO
FC36D2
4840
swap
DO
FC36D4
4240
clr .w
DO
FC36D6
4840
swap
DO
FC36D8
D0B900005648
add. 1
$5648, DO
FC36DE
23C000005FEA
move . 1
DO, $5FEA
FC36E4
7 00F
moveq. 1
#15, DO
FC36E6
4241
clr .w
D1
FC36E8
3239000029C4
move . w
$2 9C4 , D1
FC36EE
C27COOOF
and.w
#$F,D1
FC36F2
9041
sub.w
Dl, DO
FC36F4
33C000006028
move . w
DO, $6028
FC36FA
33F900002 9C4 00004DBC
move . w
$2 9C4 , $4DBC
FC3704
6000012C
bra
$FC3832
FC3708
4240
clr .w
DO
FC370A
3039000029C6
move ,w
$2 9C6, DO
FC3710
9079000016A8
sub.w
$1 6A8, DO
FC3716
4840
swap
DO
FC3718
4240
clr .w
DO
FC371A
4840
swap
DO
FC371C
80F900005FF8
divu . w
$5FF8, DO
FC3722
6708
beq
$FC372C
FC3724
303 900005FF8
move . w
$5FF8, DO
FC372A
600E
bra
$FC373A
p_width
p_width
p_width
p_height
d
Abacus Software Atari ST Internals
408
r
FC372C
4240
clr . w
DO
FC372E
3 03 900002 9C6
move . w
$29C6, DO
FC3734
90 7 900001 6A8
sub . w
$16A8, DO
FC373A
33C000005FE0
move . w
DO, $5FE0
FC3740
23F900005FEA000058EC
move . 1
$5FEA, $58EC
FC374A
4247
clr . w
D7
FC374C
600000A6
bra
$FC37F4
FC3750
427900006030
clr . w
$6030
FC3756
33FC000100006024
move . w
#1, $6024
FC375E
23F9000058EC0000574E
move . 1
$58EC, $574E
FC3768
424 6
clr . w
D6
FC376A
6030
bra
$FC379C
FC376C
207 90000574E
move . 1
$574E, A0
FC3772
3010
move . w
(A0) , DO
FC3774
720F
moveq . 1
#15, D1
FC3776
927900006028
sub.w
$6028, D1
FC377C
E260
asr . w
Dl, DO
FC377E
C07C0001
and.w
#1 , DO
FC3782
C1F900006024
muls . w
$6024, DO
FC3788
D17 900006030
add. w
DO, $6030
FC378E
54B90000574E
addq . 1
#2 , $574E
FC3794
E1F90000 602 4
asl . w
$6024
FC379A
5246
addq . w
#1 , D6
FC379C
BC7 9000056F8
cmp . w
$56F8,D6
FC37A2
6DC8
bit
$FC376C
FC37A4
4A3900005FE6
tst ,b
$5FE6
FC37AA
67 1A
beq
$FC37C6
FC37AC
303900006030
move . w
$6030, DO
FC37B2
32390000608C
move . w
$608C, Dl
FC37B8
B340
eor . w
Dl , DO
FC37BA
6608
bne
$FC37C4
FC37BC
423 900004 1B6
clr . b
$4 1B6
p_height
High resolution ?
No
Abacus Software Atari ST Internals
409
FC37C2
603A
bra
$FC37FE
FC37C4
601C
bra
$FC37E2
FC37C6
307900006030
move . w
$6030, A0
FC37CC
D1C8
add . 1
A0, A0
FC37CE
D1FC00006002
add. 1
#$6002, A0
FC37D4
0C500008
cmp.w
#8, (A0)
FC37D8
6708
beq
$FC37E2
FC37DA
4239000041B6
clr .b
$4 1B6
FC37E0
601C
bra
$FC37FE
FC37E2
303900005626
move . w
$5626, DO
FC37E8
E340
asl.w
#1 , DO
FC37EA
4 8C0
ext . 1
DO
FC37EC
D1B9000058EC
add. 1
DO, $58EC
FC37F2
5247
addq . w
#1 , D7
FC37F4
BE7 900005FEO
cmp . w
$5FE0,D7
FC37FA
6D00FF54
bit
$FC3750
FC37FE
4A39000041B6
tst .b
$4 1B6
FC3804
6736
beq
$FC383C
FC3806
537900006028
SUbq.w
#1, $6028
FC380C
4A7900006028
tst.w
$6028
FC3812
6C18
bge
$FC382C
FC3814
3039000056F8
move . w
$56F8, DO
FC381A
E340
asl.w
#1 , DO
FC381C
48C0
ext . 1
DO
FC381E
91B900005FEA
sub. 1
DO, $5FEA
FC3824
33FC000F00006028
move . w
#$F, $6028
FC382C
537900004DBC
subq.w
#1, $4DBC
FC3832
4A7 900004DBC
tst .w
$4DBC
FC3838
6E00FECE
bgt
$FC3708
FC383C
600A
bra
$FC384 8
FC383E
33F900002 9C400004DBC
move . w
$2 9C4 , $4DBC
p width
FC3848
3E3900004DBC
move . w
$4DBC,D7
Abacus Software Atari ST Internals
410
r
FC384E
CFF900006022
muls . w
$6022, D7
FC3854
4A3900005780
tst .b
$5780
Epson B/W dot-matrix printer?
FC385A
67 0A
beq
$FC3866
No
FC385C
3007
move . w
D7, DO
FC385E
4 8C0
ext . 1
DO
FC3860
81FC0002
divs . w
#2, DO
FC3864
6002
bra
$FC3868
FC3866
4240
clr . w
DO
FC3868
DE4 0
add. w
DO , D7
FC386A
3007
move . w
D7, DO
Number of points
FC386C
48C0
ext . 1
DO
FC386E
81FC0100
divs . w
#$100, DO
divided by 256
FC3872
4840
swap
DO
remainder
FC3874
13C000004E1 6
move . b
DO, $4E16
Number of points, low
byte
FC387A
3007
move . w
D7 , DO
Number of points
FC387C
48C0
ext . 1
DO
FC387E
81FC0100
divs ,w
#$100, DO
divided by 256
FC3882
13C000004E18
move . b
DO, $4E18
Number of points, high
byte
FC3888
427900005782
clr . w
$5782
FC388E
60000656
bra
$FC3EE6
FC3892
4279000060A2
clr . w
$60A2
FC3898
600005F0
bra
$FC3E8A
FC389C
4A390000575E
tst ,b
$575E
ATARI color dot-matrix
printer?
FC38A2
67000076
beq
$FC391A
No
FC38A6
4 A3 900005FE6
tst . b
$5FE6
High resolution ?
FC38AC
6600006C
bne
$FC3 91A
Yes
FC38B0
4A7 9000060A2
tst . w
$60A2
FC38B6
661E
bne
$FC38D6
FC38B8
2EBC00FD1BBE
move . 1
#$FD1BBE, ( A7 )
ESC 'X', 6
FC38BE
610007E4
bsr
$FC40A4
Send string to printer
FC38C2
4A4 0
tst . w
DO
Output OK?
Abacus Software Atari ST Internals
411
FC38C4
67 OE
beq
$FC38D4
Yes
FC38C6
33FCFFFF000004EE
move . w
#-1, $4EE
Clear dumpflg
FC38CE
7 OFF
moveq . 1
#-l , DO
Flag for error
FC38D0
6000077C
bra
$FC4 04 E
Terminate
FC38D4
6044
bra
$FC391A
FC38D6
0C79000100O060A2
cmp.w
#1, $60A2
FC38DE
661E
bne
$FC38FE
FC38E0
2EBC00FD1BC3
move . 1
#$FD1BC3, (A7)
ESC >X’, 5
FC38E6
610007BC
bsr
$FC4 0A4
Send string to printer
FC38EA
4A4 0
tst . w
DO
Output OK?
FC38EC
67 0E
beq
$FC38FC
Yes
FC38EE
33FCFFFF000004EE
move . w
#-l,$4EE
Clear dumpflg
FC38F6
70FF
moveq. 1
#-l, DO
Flag for error
FC38F8
60000754
bra
$FC4 04E
Terminate
FC38FC
601C
bra
$FC391A
FC38FE
2EBC00FD1BC8
move . 1
#$FD1BC8 , ( A7 )
ESC 'X', 3
FC3904
6100079E
bsr
$FC4 0A4
Send string to printer
FC3908
4A4 0
tst.w
DO
Output OK?
FC390A
67 0E
beq
$FC391A
Yes
FC390C
33FCFFFF000004EE
move . w
#-l,$4EE
Clear _dumpflg
FC3914
70FF
moveq. 1
o
Q
r— 1
1
=*=
Flag for error
FC3916
60000736
bra
$FC4 04E
Terminate
FC391A
4A3900005780
tst ,b
$5780
Epson B/W dot-matrix printer?
FC3920
6708
beq
$FC3 92A
No
FC3922
2EBC00FD1BCD
move . 1
#$FD1BCD, (A7 )
ESC ' L', bit image 960 dots/line
FC3928
6006
bra
$FC3 930
A
Abacus Software Atari ST Internals
412
FC392A
2EBC00FD1BD1
move . 1
#$FD1BD1 , (A7)
FC3930
61000772
bsr
$FC40A4
FC3934
4A4 0
tst .w
DO
FC3936
67 0E
beq
$FC394 6
FC3938
33FCFFFF000004EE
move . w
#-l, $4EE
FC3940
7 OFF
moveq . 1
#-l, DO
FC3942
6000070A
bra
5FC404E
FC3946
103900004E16
move . b
$4E16, DO
FC394C
4880
ext . w
DO
FC394E
3E80
move.w
DO, (A7 )
FC3950
61000706
bsr
$FC4 058
FC3954
4A40
tst .w
DO
FC3956
670E
beq
$FC3 966
FC3958
33FCFFFF000004EE
move . w
#-l , $4EE
FC3960
7 OFF
moveq. 1
#-l, DO
FC3962
600006EA
bra
$FC404E
FC3966
103900004E18
move . b
$4E18, DO
FC396C
4880
ext . w
DO
FC396E
3E80
move . w
DO, ( A7 )
FC3970
610006E6
bsr
$FC4058
FC3974
4A4 0
tst .w
DO
FC3976
670E
beq
$FC3986
FC3978
33FCFFFF000004EE
move . w
#-l,$4EE
FC3980
7 OFF
moveq . 1
4t=
1
M
a
o
FC3982
600006CA
bra
$FC404E
FC3986
13FC000100006000
move . b
#1, $6000
FC398E
2 3F900005 64 800005FEA
move . 1
$5648, $5FEA
FC3998
33F90000574C00006028
move . w
$574C, $6028
ESC ' Y ' , bit image 1280 dots/line
Send string to printer
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Number of points, low-byte
Output character
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Number of points, high-byte
Output character
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Abacus Software Atari ST Internals
413
FC39A2
427900001 6A6
clr . w
$1 6A6
FC39A8
600004B0
bra
$FC3E5A
FC39AC
4247
clr . w
D7
FC39AE
600C
bra
$FC3 9BC
FC39B0
3047
move . w
D7, A0
FC39B2
D1FC000057 84
add . 1
#$5784, AO
FC39B8
4210
clr . b
(A0)
FC39BA
5247
addq . w
#1 , D7
FC39BC
BE7C0008
cmp . w
#8 , D7
FC39C0
6DEE
bit
$FC39B0
FC39C2
4247
clr .w
D7
FC39C4
601E
bra
$FC39E4
FC39C6
3047
move . w
D7, A0
FC39C8
D1C8
add. 1
A0, A0
FC39CA
D1FC00004E1A
add. 1
#$4E1A, A0
FC39D0
30BC0007
move . w
#7, (A0)
FC39D4
3047
move . w
D7, A0
FC39D6
D1C8
add. 1
A0, A0
FC39D8
D1FC00005FEE
add. 1
#$5FEE, AO
FC39DE
30BC0008
move . w
#8, (AO)
FC39E2
5247
addq . w
#1 , D7
FC39E4
BE7C0004
cmp.w
#4 , D7
FC39E8
6DDC
bit
$FC3 9C6
FC39EA
4240
clr .w
DO
FC39EC
3039000029C6
move . w
$29C6, DO
p height
FC39F2
907 900001 6A8
sub . w
$1 6A8 , DO
FC39F8
4840
swap
DO
FC39FA
4240
clr .w
DO
FC39FC
4840
swap
DO
A
Abacus Software Atari ST Internals
414
FC39FE
80F900005FF8
divu . w
$5FF8 , DO
FC3A04
6708
beq
$FC3A0E
FC3A06
303900005FF8
move . w
$5FF8 , DO
FC3A0C
600E
bra
$FC3A1C
FC3A0E
4240
clr .w
DO
FC3A10
303900002 9C6
move . w
$2 9C6, DO
FC3A16
907 900001 6A8
sub . w
$1 6A8 , DO
FC3A1C
33C000005FEO
move . w
DO, $5FE0
FC3A22
4240
clr .w
DO
FC3A24
303900002 9C6
move . w
$2 9C6, DO
FC3A2A
9079000016A8
sub.w
$1 6A8 , DO
FC3A30
4840
swap
DO
FC3A32
4240
clr .w
DO
FC3A34
4840
swap
DO
FC3A36
80F900005FF8
divu .w
$5FF8, DO
FC3A3C
67 0C
beq
$FC3A4A
FC3A3E
33F900005FF800005FEO
move . w
$5FF8, $5FE0
FC3A48
601A
bra
$FC3A64
FC3A4A
4240
clr .w
DO
FC3A4C
3039000029C6
move . w
$2 9C6, DO
FC3A52
9079000016A8
sub.w
$1 6A8 , DO
FC3A58
33C000005FE0
move . w
DO, $5FE0
FC3A5E
4239000060A0
clr .b
$60A0
FC3A64
23F900005FEA000058EC
move . 1
$5FEA, S58EC
FC3A6E
4247
clr . w
D7
FC3A70
6000011C
bra
$FC3B8E
FC3A74
427900006030
clr .w
$6030
FC3A7A
33FC000100006024
move . w
#1, $6024
FC3A82
23F9000058EC0000574E
move . 1
$58EC, $574E
p_height
p_height
p_height
Abacus Software Atari ST Internals
FC3A8C
4246
clr.w
D6
FC3A8E
6030
bra
5FC3AC0
FC3A90
20790000574E
move . 1
$574E, A0
FC3A96
3010
move . w
(A0) , DO
FC3A98
720F
moveq. 1
#15, D1
FC3A9A
927900006028
sub . w
$6028, D1
FC3AA0
E260
asr.w
Dl, DO
FC3AA2
C07C0001
and. w
#1 , DO
FC3AA6
C1F900006024
muls . w
$6024, DO
FC3AAC
D17 900006030
add. w
DO, $6030
FC3AB2
54B90000574E
addq . 1
#2 , $57 4E
FC3AB8
E1F900006024
asl.w
$6024
FC3ABE
5246
addq . w
#1 , D6
FC3AC0
BC 7 900005 6F8
cmp.w
$56F8,D6
FC3AC6
6DC8
bit
$FC3A90
FC3AC8
4A3900005FE6
tst .b
$5FE6
High resolution ?
FC3ACE
672C
beq
$FC3AFC
No
FC3AD0
303900006030
move . w
$6030, DO
FC3AD6
32390000608C
move . w
$608C,D1
FC3ADC
B340
eor.w
Dl, DO
FC3ADE
660C
bne
$FC3AEC
FC3AE0
207 900002 9D8
move . 1
$29D8, A0
p masks, address of half-tone mask
FC3AE6
1010
move . b
(A0) , DO
FC3AE8
4880
ext . w
DO
FC3AEA
6002
bra
$FC3AEE
FC3AEC
4240
clr.w
DO
FC3AEE
3247
move ,w
D7 , A1
FC3AF0
D3FC00005784
add. 1
#$5784, A1
FC3AF6
1280
move . b
DO, (Al)
FC3AF8
60000082
bra
$FC3B7C
Abacus Software Atari ST Internals
416
FC3AFC
3047
move . w
D7, A0
FC3AFE
D0C8
add.w
A0, A0
FC3B00
D1FC00005784
add.l
#$5784, AO
FC3B06
327900006030
move . w
$6030, A1
FC3B0C
D3C9
add. 1
Al, A1
FC3B0E
D3FC00006002
add. 1
#$6002, A1
FC3B14
3251
move . w
(Al) ,A1
FC3B16
D2C9
add.w
Al , Al
FC3B18
D3F900002 9D8
add. 1
$29D8, Al
FC3B1E
1091
move .b
(Al) , (A0)
FC3B20
3047
move .w
D7 , A0
FC3B22
D0C8
add.w
A0, A0
FC3B24
D1FC00005784
add. 1
#$5784, A0
FC3B2A
327900006030
move .w
$6030, Al
FC3B30
D3C9
add.l
Al, Al
FC3B32
D3FC00006002
add. 1
#$6002, Al
FC3B38
3251
move . w
(Al) , Al
FC3B3A
D2C9
add.w
Al, Al
FC3B3C
D3F900002 9D8
add. 1
$29D8, Al
FC3B42
116900010001
move ,b
1 (Al) , 1 (AO)
FC3B48
3047
move . w
D7 , A0
FC3B4A
D1C8
add. 1
AO, A0
FC3B4C
D1FC00004E1A
add. 1
#$4E1A, AO
FC3B52
327900006030
move . w
$6030, Al
FC3B58
D3C9
add. 1
Al, Al
FC3B5A
D3FC00005628
add. 1
#$5628, Al
FC3B60
3091
move . w
(Al) , (A0)
FC3B62
3047
move . w
D7, A0
FC3B64
D1C8
add. 1
AO, AO
FC3B66
D1FC00005FEE
add. 1
#$5FEE, AO
FC3B6C
327900006030
move . w
$6030, Al
FC3B72
D3C 9
add . 1
Al, Al
plus p_masks
plus p_masks
Abacus Software Atari ST Internals
417
FC3B74
D3FC000057 60
add . 1
#$5760, A1
FC3B7A
3091
move . w
(Al) , (A0)
FC3B7C
303900005626
move . w
$5626, DO
FC3B82
E34 0
asl . w
#1 , DO
FC3B84
4 8C0
ext . 1
DO
FC3B86
D1B9000058EC
add . 1
DO, $58EC
FC3B8C
5247
addq . w
#1 , D7
FC3B8E
BE7 900005FEO
cmp . w
$5FE0 , D7
FC3B94
6DOOFEDE
bit
$FC3A7 4
FC3B98
4A390000575E
tst .b
$575E
FC3B9E
67 0001BE
beq
$FC3D5E
FC3BA2
4A3900005FE6
tst .b
$5FE6
FC3BA8
660001B4
bne
$FC3D5E
FC3BAC
4247
clr.w
D7
FC3BAE
600001A4
bra
$FC3D54
FC3BB2
423900005FF6
clr . b
$5FF6
FC3BB8
4A7 9000060A2
tst .w
$60A2
FC3BBE
6626
bne
$FC3BE6
FC3BC0
3047
move .w
D7 , A0
FC3BC2
D1C8
add. 1
A0, A0
FC3BC4
227C00004E1A
move . 1
#$4E1A, Al
FC3BCA
30309800
move . w
0 (A0, Al .1) , DO
FC3BCE
4 8C0
ext . 1
DO
FC3BD0
81FC0002
divs . w
#2, DO
FC3BD4
4840
swap
DO
FC3BD6
4A4 0
tst .w
DO
FC3BD8
6708
beq
$FC3BE2
FC3BDA
13FC000100005FF6
move . b
#1, $5FF6
FC3BE2
600000F0
bra
$FC3CD4
FC3BE6
OC790001000060A2
cmp . w
#1, $60A2
ATARI color dot-matrix printer?
No
High resolution ?
Yes
Abacus Software Atari ST Internals
418
r
FC3BEE
6600008C
bne
$FC3C7C
FC3BF2
3047
move . w
D7, A0
FC3BF4
D1C8
add . 1
A0, A0
FC3BF6
D1FC00004E1A
add. 1
#$4E1A, A0
FC3BFC
OC500006
cmp . w
#6, (A0)
FC3C00
6630
bne
$FC3C32
FC3C02
3047
move . w
D7, A0
FC3C04
D1C8
add . 1
A0, A0
FC3C06
D1FC00005FEE
add. 1
#$5FEE, A0
FC3C0C
OC500008
cmp.w
#8, (A0)
FC3C10
6C20
bge
$FC3C32
FC3C12
3047
move . w
D7 , A0
FC3C14
D0C8
add.w
A0, A0
FC3C16
D1FC00005784
add. 1
#$5784, AO
FC3C1C
02100001
and.b
#1, (AO)
FC3C20
3047
move . w
D7, AO
FC3C22
D0C8
add.w
AO, AO
FC3C24
D1FC00005784
add. 1
#$5784, AO
FC3C2A
022800040001
and.b
#4, 1(A0)
FC3C30
6048
bra
$FC3C7A
FC3C32
3047
move . w
D7, AO
FC3C34
D1C8
add. 1
AO, AO
FC3C36
D1FC00004E1A
add. 1
#$4E1A, AO
FC3C3C
0C500002
cmp.w
#2, (AO)
FC3C40
6730
beq
$FC3C72
FC3C42
3047
move . w
D7, AO
FC3C44
D1C8
add. 1
AO, AO
FC3C46
D1FC00004E1A
add. 1
#$4E1A, AO
FC3C4C
0C500003
cmp . w
#3, (AO)
FC3C50
6720
beq
$FC3C72
FC3C52
3047
move . w
D7, AO
Abacus Software Atari ST Internals
419
FC3C54
D1C8
add . 1
AO, AO
FC3C56
D1FC00004E1A
add. 1
#$4 El A, AO
FC3C5C
0C500006
cmp . w
#6, (A0)
FC3C60
6710
beq
SFC3C72
FC3C62
3047
move . w
D7, A0
FC3C64
D1C8
add . 1
A0, A0
FC3C66
D1FC00004E1A
add . 1
#$4E1A, AO
FC3C6C
OC500007
cmp. w
#7, (A0)
FC3C70
6608
bne
$FC3C7A
FC3C72
13FC000100005FF6
move . b
#1 , $5FF6
FC3C7A
6058
bra
$FC3CD4
FC3C7C
3047
move . w
D7, AO
FC3C7E
D1C8
add. 1
A0, A0
FC3C80
D1FC00004E1A
add. 1
#$4E1A, A0
FC3C86
0C500006
cmp.w
#6, (AO)
FC3C8A
6630
bne
$FC3CBC
FC3C8C
3047
move . w
D7, AO
FC3C8E
D1C8
add. 1
AO, AO
FC3C90
D1FC00005FEE
add. 1
#$5FEE, AO
FC3C96
OC500008
cmp.w
#8, (AO)
FC3C9A
6C20
bge
$FC3CBC
FC3C9C
3047
move . w
D7 , AO
FC3C9E
D0C8
add.w
AO, AO
FC3CA0
D1FC00005784
add. 1
#$5784, AO
FC3CA6
02100004
and.b
#4, (AO)
FC3CAA
3047
move . w
D7, AO
FC3CAC
D0C8
add.w
AO, AO
FC3CAE
D1FC00005784
add. 1
#$5784, AO
FC3CB4
022800010001
and.b
#1,1 (AO)
FC3CBA
6018
bra
$FC3CD4
J
Abacus Software Atari ST Internals
420
FC3CBC
3047
move . w
FC3CBE
D1C8
add . 1
FC3CC0
D1FC00004E1A
add . 1
FC3CC6
0C500003
cmp . w
FC3CCA
6F08
ble
FC3CCC
13FC000100005FF6
move . b
FC3CD4
4A3900005FF6
t st . b
FC3CDA
67 1A
beq
FC3CDC
3047
move . w
FC3CDE
D0C8
add. w
FC3CE0
D1FC00005784
add. 1
FC3CE6
4210
clr . b
FC3CE8
3047
move . w
FC3CEA
D0C8
add.w
FC3CEC
D1FC00005784
add. 1
FC3CF2
42280001
clr . b
FC3CF6
2 07 90 0002 9D8
move . 1
FC3CFC
3247
move . w
FC3CFE
D3C9
add. 1
FC3D00
D3FC00005FEE
add. 1
FC3D06
3251
move . w
FC3D08
D2C9
add.w
FC3D0A
10309000
move ,b
FC3D0E
4880
ext . w
FC3D10
3F00
move . w
FC3D12
3047
move . w
FC3D14
D0C8
add.w
FC3D16
D1FC00005784
add. 1
FC3D1C
1010
move . b
FC3D1E
805F
or .w
FC3D20
1080
move . b
FC3D22
207 900002 9D8
move . 1
D7, AO
AO, AO
#$4E1A, AO
#3, (AO)
$FC3CD4
#1 , $5FF6
$5FF6
$FC3CF6
D7, AO
AO, AO
#$5784, AO
(AO)
D7 , AO
AO, AO
#$5784, AO
KAO)
$2 9D8, AO pjnasks
D7,A1
Al, A1
#$5FEE,A1
(Al) ,A1
Al, Al
0 ( AO , Al . w) , DO
DO
DO, - (A7)
D7 , AO
AO, AO
#$5784, AO
(AO) , DO
(A7 ) +, DO
DO, (AO)
$2 9D8, AO p_masks
Abacus Software Atari ST Internals
421
FC3D28
3247
move . w
D7,A1
FC3D2A
D3C9
add . 1
Al, A1
FC3D2C
D 3 FC 000 05 FEE
add . 1
#$5FEE,A1
FC3D32
3251
move . w
(Al) ,A1
FC3D34
D2C9
add. w
Al, Al
FC3D36
10309001
move .b
1 ( A0 , Al . w) , DO
FC3D3A
4880
ext . w
DO
FC3D3C
3F00
move .w
DO, - (A7)
FC3D3E
3047
move . w
D7, A0
FC3D40
D0C8
add.w
A0, A0
FC3D42
D1FC000057 84
add . 1
#$5784, A0
FC3D48
10280001
move .b
1 (A0) , DO
FC3D4C
805F
or .w
(A7) +, DO
FC3D4E
11400001
move . b
DO, 1 (A0)
FC3D52
5247
addq . w
#1 , D7
FC3D54
BE7 9O0005FE0
cmp.w
$5FE0,D7
FC3D5A
6D00FE56
bit
$FC3BB2
FC3D5E
7E04
moveq. 1
#4 , D7
FC3D60
6000008E
bra
$FC3DF0
FC3D64
42390000414C
clr ,b
$414C
FC3D6A
33FC 00800000602 6
move . w
#$80, $6026
FC3D72
4246
clr.w
D6
FC3D74
603E
bra
$FC3DB4
FC3D76
207C00005784
move . 1
#$5784, A0
FC3D7C
10306000
move . b
0 (A0, D6.w) , DO
FC3D80
4880
ext . w
DO
FC3D82
7207
moveq . 1
#7 , D1
FC3D84
9247
sub . w
D7,D1
FC3D86
E260
asr.w
Dl, DO
FC3D88
C07C0001
and.w
#1 , DO
A
Abacus Software Atari ST Internals
422
r
FC3D8C
C1F900006026
muls . w
$6026, DO
FC3D92
12390000414C
move . b
$414C, D1
FC3D98
D200
add.b
DO, D1
FC3D9A
13C100004 14C
move . b
D1 , $ 4 14C
FC3DA0
303900006026
move . w
$6026, DO
FC3DA6
4 8C0
ext . 1
DO
FC3DA8
81FC0002
divs . w
#2, DO
FC3DAC
33C00000602 6
move . w
DO, $6026
FC3DB2
5246
addq . w
#1 , D6
FC3DB4
BC7C0008
cmp.w
#8, D6
FC3DB8
6DBC
bit
$FC3D7 6
FC3DBA
10390000414C
move . b
$4 14C, DO
FC3DC0
4880
ext . w
DO
FC3DC2
3E80
move . w
DO, <A7)
FC3DC4
61000292
bsr
$FC4058
Output character
FC3DC8
4A40
tst . w
DO
Output OK?
FC3DCA
67 0E
beq
$FC3DDA
Yes
FC3DCC
33FCFFFF000004EE
move . w
#-l,$4EE
Clear dumpflg
FC3DD4
70FF
moveq , 1
#-l, DO
Flag for error
FC3DD6
60000276
bra
$FC404E
Terminate
FC3DDA
4A3900006000
tst . b
$6000
FC3DE0
6704
beq
$FC3DE6
FC3DE2
4240
clr .w
DO
FC3DE4
6002
bra
$FC3DE8
FC3DE6
7001
moveq . 1
#1 , DO
FC3DE8
13C000006000
move . b
DO, $6000
FC3DEE
5247
addq . w
#1 , D7
FC3DF0
303900006022
move . w
$6022, DO
FC3DF6
5840
addq . w
#4, DO
FC3DF8
BE40
cmp . w
DO, D7
Abacus Software Atari ST Internals
423
FC3DFA
6D0CFF68
bit
$FC3D64
Epson B/W dot-matrix printer?
FC3DFE
4 A39000057 80
tst . b
$5780
FC3E04
6728
beq
$FC3E2E
No
FC3E06
4A3900006000
tst . b
$6000
FC3E0C
6720
beq
$FC3E2E
FC3E0E
103 900004 14C
move . b
$4 14C, DO
FC3E14
4880
ext . w
DO
FC3E16
3E80
move . w
DO, ( A7 )
FC3E18
6100023E
bsr
$FC4 058
Output character
FC3E1C
4A40
tst .w
DO
Output OK?
FC3E1E
67 0E
beq
$FC3E2E
Yes
FC3E20
33FCFFFF000004EE
move . w
#-l, $4EE
Clear _dumpflg
FC3E28
7 0FF
moveq. 1
#-l , DO
Flag for error
FC3E2A
60000222
bra
$FC404E
Terminate
FC3E2E
527900006028
addq . w
#1, $6028
FC3E34
0C79000F00006028
cmp.w
#15, $6028
FC3E3C
6F1 6
ble
$FC3E54
FC3E3E
3039000056F8
move . w
$56F8, DO
FC3E44
E34 0
asl .w
#1, DO
FC3E46
4 8C0
ext . 1
DO
FC3E48
D1B900005FEA
add. 1
DO, $5FEA
FC3E4E
427900006028
clr .w
$6028
FC3E54
5279000016A6
addq . w
#1, $16A6
FC3E5A
3039000016A6
move . w
$16A6, DO
FC3E60
B07 900004DBC
cmp . w
$4DBC, DO
FC3E66
6D00FB4 4
bit
$FC3 9AC
FC3E6A
3EBC000D
move . w
#$D, (A7)
Carriage Return
FC3E6E
610001E8
bsr
$FC4058
Output character
FC3E72
4A4 0
tst . w
DO
Output OK?
FC3E74
67 0E
beq
$FC3E84
Yes
FC3E76
33FCFFFF000004EE
move . w
#-l,$4EE
Clear dumpflg
J
Abacus Software Atari ST Internals
424
r
FC3E7E
7 OFF
moveq . 1
#-l, DO
Flag for error
FC3E80
600001CC
bra
$FC4 04E
Terminate
FC3E84
52 7 9000060A2
addq . w
#1, $60A2
FC3E8A
4A390000575E
tst .b
$575E
ATARI color dot-matrix printer?
FC3E90
67 0C
beq
$FC3E9E
No
FC3E92
4A3900005FE6
tst .b
$5FE6
High resolution ?
FC3E98
6604
bne
$FC3E9E
Yes
FC3E9A
7003
moveq . 1
#3, DO
FC3E9C
6002
bra
$FC3EA0
FC3E9E
7001
moveq . 1
#1 , DO
FC3EA0
B07 90000 60A2
cmp.w
$60A2 , DO
FC3EA6
6E00F9F4
bgt
$FC389C
FC3EAA
2EBC00FD1BD5
move . 1
#$FD1BD5 , (A7)
ESC '3', 1, 1/216" line spacing
FC3EB0
610001F2
bsr
$FC4 0A4
Send string to printer
FC3EB4
4A40
tst .w
DO
Output OK?
FC3EB6
670E
beq
$FC3EC6
Yes
FC3EB8
33FCFFFF000004EE
move . w
#-l,$4EE
Clear _dumpflg
FC3EC0
7 OFF
moveq. 1
#-l, DO
Flag for error
FC3EC2
6000018A
bra
$FC4 04E
Terminate
FC3EC6
3EBC000A
move . w
#$ A, ( A7)
Linefeed
FC3ECA
6100018C
bsr
$FC4 058
Output character
FC3ECE
4A4 0
tst . w
DO
Output OK?
FC3ED0
67 0E
beq
$FC3EE0
Yes
FC3ED2
33FCFFFF000004EE
move . w
#-1, $4 EE
Clear _dumpflg
FC3EDA
7 OFF
moveq . 1
#-l , DO
Flag for error
FC3EDC
60000170
bra
$FC404E
Terminate
FC3EE0
527900005782
addq . w
#1, $5782
FC3EE6
4A3900005FFE
tst ,b
$5FFE
Quality mode?
Abacus Software Atari ST Internals
425
FC3EEC
6704
beq
$FC3EF2
FC3EEE
7001
moveq . 1
#1 , DO
FC3EF0
6002
bra
$FC3EF 4
FC3EF2
7002
moveq . 1
#2, DO
FC3EF4
B0 7 9000057 82
cmp.w
$5782, DO
FC3EFA
6E00F996
bgt
$FC38 92
FC3EFE
4A3900005FFE
tst .b
$5FFE
FC3F04
674E
beq
$FC3F54
FC3F06
4247
clr . w
D7
FC3F08
6038
bra
$FC3F42
FC3F0A
2EBC00FD1BDA
move . 1
#$FD1BDA, (A7 )
FC3F10
61000192
bsr
$FC4 0A4
FC3F14
4A4 0
tst . w
DO
FC3F16
670E
beq
$FC3F2 6
FC3F18
33FCFFFF000004EE
move . w
#-l, $4EE
FC3F20
70FF
moveq. 1
#-l, DO
FC3F22
6000012A
bra
$FC404E
FC3F26
3EBC000A
move . w
#$A, (A7 )
FC3F2A
6100012C
bsr
$FC4058
FC3F2E
4A4 0
tst .w
DO
FC3F30
67 0E
beq
$FC3F40
FC3F32
33FCFFFF000004EE
move . w
#-l,$4EE
FC3F3A
7 0FF
moveq. 1
#-l , DO
FC3F3C
60000110
bra
$FC404E
FC3F40
5247
addq . w
#1, D7
FC3F42
4A3900005780
tst ,b
$5780
FC3F48
6704
beq
$FC3F4E
Yes
Quality mode?
Yes
ESC '3', 1, 1/216" line spacing
Send string to printer
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Linefeed
Output character
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Epson B/W dot-matrix printer?
No
J
Abacus Software Atari ST Internals
426
FC3F4A
7002
moveq . 1
#2, DO
FC3F4C
6002
bra
$FC3F50
FC3F4E
7001
moveq . 1
#1 , DO
FC3F50
BE4 0
cmp.w
DO, D7
FC3F52
6DB6
bit
$FC3F0A
FC3F54
4A39000060A0
tst .b
$60A0
FC3F5A
6738
beq
$FC3F94
FC3F5C
2EBC00FD1BDF
move . 1
#$FD1BDF, ( A7 )
ESC '1', 7/72" line spacing
FC3F62
61000140
bsr
$FC4 0A4
Send string to printer
FC3F66
4A40
tst . w
DO
Output OK?
FC3F68
670E
beq
5FC3F78
Yes
FC3F6A
33FCFFFF000004EE
move . w
#-l, $4EE
Clear _dumpflg
FC3F72
7 0FF
moveq. 1
#-l, DO
Flag for error
FC3F74
600000D8
bra
$FC404E
Terminate
FC3F78
3EBCOOOA
move . w
#$A, (A7)
Linefeed
FC3F7C
610000DA
bsr
$FC4058
Output character
FC3F80
4A40
tst .w
DO
Output OK?
FC3F82
670E
beq
$FC3F92
Yes
FC3F84
33FCFFFF000004EE
move . w
#-l,$4EE
Clear _dumpflg
FC3F8C
7 0FF
moveq . 1
#-l , DO
Flag for error
FC3F8E
600000BE
bra
$FC4 04E
Terminate
FC3F92
6060
bra
$FC3FF4
FC3F94
4247
clr . w
D7
FC3F96
6038
bra
3FC3FD0
FC3F98
2EBC00FD1BE3
move . 1
#$FD1BE3 , ( A7 )
ESC '3', 1, 1/216" line spacing
FC3F9E
61000104
bsr
$FC4 0A4
Send string to printer
Abacus Software Atari ST Internals
427
FC3FA2
4A40
tst . w
DO
FC3FA4
67 OE
beq
$FC3FB4
FC3FA6
33FCFFFF0 00 00 4 EE
move . w
#-l, $4EE
FC3FAE
7 OFF
moveq . 1
#-l , DO
FC3FB0
6000009C
bra
$FC404E
FC3FB4
3EBCOOOA
move . w
#$A, ( A7 )
FC3FB8
6100009E
bsr
$FC4058
FC3FBC
4A40
tst . w
DO
FC3FBE
67 OE
beq
$FC3FCE
FC3FC0
33FCFFFF000004EE
move . w
#-i,$4EE
FC3FC8
70FF
moveq . 1
#-l, DO
FC3FCA
60000082
bra
$FC4 04E
FC3FCE
5247
addq . w
#1 , D7
FC3FD0
4A3900005780
tst .b
$5780
FC3FD6
670E
beq
$FC3FE6
FC3FD8
303900005FEO
move . w
$5FE0 , DO
FC3FDE
C1FC000 6
muls .w
#6, DO
FC3FE2
5740
subq.w
#3, DO
FC3FE4
600A
bra
$FC3FF0
FC3FE6
303900005FE0
move . w
$5FE0, DO
FC3FEC
E54 0
asl .w
#2, DO
FC3FEE
5540
subq . w
#2, DO
FC3FF0
BE40
cmp . w
DO, D7
FC3FF2
6DA4
bit
$FC3F98
FC3FF4
303900004E10
move . w
$4E10, DO
FC3FFA
E34 0
asl.w
#1 , DO
FC3FFC
4 8C0
ext . 1
DO
FC3FFE
D1B900005648
add. 1
DO, $5648
FC4004
303 900005FF8
move . w
$5FF8, DO
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Linefeed
Output character
Output OK?
Yes
Clear _dumpflg
Flag for error
Terminate
Epson B/W dot-matrix printer?
No
Abacus Software Atari ST Internals
428
FC400A
D1 7 900001 6A8
add . w
DO, $16A8
FC4010
4240
clr . w
DO
FC4012
303 900002 9C6
move . w
$2 9C6, DO
p height
FC4018
B07 900001 6A8
cmp.w
$1 6A8 , DO
FC401E
6200F67C
bhi
$FC369C
FC4022
2EBC00FD1BE8
move . 1
#$FD1BE8, (A7 )
ESC '2‘, 1/6" line spacing
FC4028
6100007A
bsr
$FC4 0A4
Send string to printer
FC402C
4A390000575E
tst .b
$575E
ATARI color dot-matrix printer?
FC4032
6710
beq
$FC4 04 4
No
FC4034
4A3900005FE6
tst .b
$5FE6
High resolution ?
FC403A
6608
bne
$FC4 04 4
Yes
FC403C
2EBC00FD1BEC
move . 1
#$FD1BEC, ( A7 )
ESC 'X', 0
FC4042
6160
bsr
$FC4 0A4
Send string to printer
FC4044
33FCFFFF000004EE
move . w
#-l,$4EE
Clear _dumpflg
FC404C
4240
clr .w
DO
OK
FC404E
4A9F
tst . 1
<A7) +
FC4050
4CDF30CO
movem. 1
(A7 ) +, D6-D7/A4-A5
Restore registers
FC4054
4E5E
unlk
A6
FC4056
4E75
rts
********************************************************
Output character to printer
FC4058
4E56FFFC
link
A6, #-4
FC405C
4 A3 900002 9BC
tst .b
$2 9BC
Printer port
FC4062
6722
beq
$FC4 08 6
RS 232 ?
FC4064
102E0009
move . b
9 ( A6) , DO
Get character
FC4068
4880
ext . w
DO
FC406A
3E80
move . w
DO, ( A7 )
on the stack
FC406C
102E0009
move . b
9 ( A6) , DO
FC4070
4880
ext . w
DO
FC4072
3FOO
move . w
DO, - (A7)
(again ?)
FC4074
4EB900FC40E4
jsr
SFC40E4
Output character to printer
FC407A
548F
addq . 1
#2, A7
Abacus Software Atari ST Internals
429
FC407C
4A40
tst . w
DO
FC407E
6604
bne
$FC 4 0 8 4
FC 4 0 8 0
7 OFF
moveq . 1
#-l , DO
FC4082
60 1C
bra
$FC4 0A0
FC4084
6018
bra
$FC409E
FC4086
102E0009
move .b
9 (A6) , DO
FC408A
4880
ext . w
DO
FC408C
3E80
move . w
DO, ( A7 )
FC408E
102E0009
move . b
9 ( A6) , DO
FC4092
4880
ext . w
DO
FC4094
3FO0
move . w
DO,- (A7)
FC4096
4EB900FC4 112
jsr
$FC4112
FC409C
548F
addq . 1
#2 , A7
FC409E
4240
clr .w
DO
FC40A0
4E5E
unlk
A6
FC40A2
4E75
rts
FC40A4
4E56FFFC
link
A6,#-4
FC40A8
6018
bra
$FC40C2
FC40AA
206E0008
move . 1
8 ( A6) , A0
FC40AE
1010
move . b
(A0) , DO
FC40B0
4880
ext . w
DO
FC40B2
3E80
move . w
DO, ( A7 )
FC40B4
61A2
bsr
$FC4058
FC40B6
52AE0008
addq . 1
#1 , 8 ( A6)
FC40BA
4A4 0
'tst .w
DO
FC40BC
6704
beq
$FC4 0C2
FC40BE
7 0FF
moveq . 1
#-l, DO
FC40C0
600C
bra
$FC4 0CE
OK ?
Yes
Flag for error
Terminate
OK
Get character
on stack
(again ?)
RS 232 output
OK
Send string to printer
String address
Character of the string
on stack
Output character
Pointer to next character
Output OK?
Yes
Flag for error
Abacus Software Atari ST Internals
FC40C2 206E0008
FC40C6 OCIOOOFF
FC40CA 66DE
FC40CC 4240
FC40CE 4E5E
FC40D0 4E75
move .1 8 ( A6) , AO
cmp.b #$FF, (AO)
bne $FC4 OAA
clr.w DO
unlk A6
rts
FC40D2 48E71F1E
FC40D6 9BCD
FC40D8 206D0506
FC40DC 4E90
FC40DE 4CDF78F8
FC40E2 4E75
movem.l D3-D7/A3-A6, - (A7)
sub.l A5,A5
move . 1 $50 6 (AS), AO
jsr (AO)
movem.l (A7) +, D3-D7/A3-A6
rts
FC40E4 302F0006
FC40E8 48E71F1E
FC40EC 3F00
FC40EE 3F00
FC40F0 9BCD
FC40F2 206D050A
FC40F6 4E90
FC40F8 584F
FC40FA 4CDF78F8
FC40FE 4E75
move . w 6 (A7) , DO
movem.l D3-D7/A3-A6, - (A7 )
move.w D0,-(A7)
move.w D0,-(A7)
sub.l A5,A5
move . 1 $50A ( A5) , AO
jsr (AO)
addq.w #4,A7
movem.l (A7) +, D3-D7/A3-A6
rts
*****************************************************
FC4100 48E71F1E movem.l D3-D7/A3-A6, - ( A7 )
FC4104 9BCD sub.l A5,A5
FC4106 206D050E move . 1 $50E(A5),A0
FC410A 4E90 jsr (AO)
String address
End criterium reached?
No
OK
Get printer status
Save registers
Clear A5
prt_stat
Jump via vector
Restore registers
Printer output
Character to output
Save registers
Character on stack
(again ?)
Clear A5
prt_vec
Jump via vector
Correct stack pointer
Restore registers
RS 232 output status
Save regisers
Clear A5
aux_stat
Jump via vector
Abacus Software Atari ST Internals
FC410C 4CDF78F8
FC4110 4E75
movem.l (A7 ) + , D3-D7 /A3-A6
rts
FC4112 302F0006
48E71F1E
FC4116
FC411A
FC411C
FC411E
FC4120 206D0512
FC4124 4E90
FC4126
FC4128
FC412C
4CDF78F8
move . w 6 ( A7 ) , DO
movem.l D3-D7 /A3-A6, - ( A7 )
move . w DO , - ( A7)
move . w DO, - (A7)
sub.l A5,A5
move . 1 $512(A5),A0
jsr (AO)
addq.w #4,A7
movem .1 ( A7 ) + , D3-D7 / A3-A6
FC412E
207 900002 93E
move . 1
$2 93E, A0
FC4134
3028000A
move . w
10 (A0) ,D0
FC4138
B07C0013
cmp.w
#$13, DO
FC413C
6236
bhi
$FC4174
FC413E
E340
asl.w
#1 , DO
FC4140
307B000A
move . w
$FC414C(PC,D0.w) , A0
FC4144
D1FC00FC4348
add. 1
#$FC4348 , A0
FC414A
4ED0
jmp
(A0)
FC414C 0000
dc . w
$FC4348-$FC4348
FC414E FFD8
dc .w
$FC4320-$FC4348
FC4150 0012
dc .w
$FC435A-$FC4348
FC4152 000C
dc .w
$FC4354-$FC4348
FC4154 001A
dc .w
$FC 4362-$ FC 4348
FC4156 002E
dc .w
$FC4376-$FC4348
Restore registers
RS 232 output
Character to output
Save registers
Character on stack
(again ?)
Clear A5
auxvec
Jump via vector
Correct stack pointer
Restore registers
VDI ESCAPE functions
Address of the CONTRL array
Function number
Greater than 19 ?
Yes
Get relative address from the table
Add base address
Execute routine
Address of the VDI escape functions
0, rts
1, Inquire addressable alpha character cells
2, Exit alpha mode
3, Enter alpha mode
4, Alpha cursor up
5, Alpha cursor down
Abacus Software Atari ST Internals
432
FC4158
0048
dc . w
$FC 4390-$ FC 4348
6,
Alpha cursor right
FC415A
0062
dc . w
$FC43AA-$FC4348
7,
Alpha cursor left
FC415C
0076
dc . w
$FC436E-$FC4348
8,
Home alpha cursor
FC415E
007E
dc .w
$FC43C6-$FC4348
9,
Erase to end of alpha screen
FC4160
00AA
dc .w
$FC43F2-$FC4348
10,
Erase to end of alpha text line
FC4162
0114
dc . w
$FC445C-$FC4348
11,
Direct alpha cursor address
FC4164
0128
dc .w
$FC4470-$FC4348
12,
Output cursor addressable alpha text
FC4.166
014E
dc .w
$FC4496-$FC4348
13,
Reverse video on
FC4168
0158
dc .w
$FC44A0-$FC4348
14,
Reverse video off
FC416A
0162
dc . w
$FC4 4AA-$FC434 8
15,
Inquire current alpha cursor address
FC416C
018C
dc .w
$FC44D4-$FC4348
16,
Inquire tablet status
FC416E
0002
dc ,w
$FC434A-$FC4348
17,
Hardcopy
FC4170
01A4
dc .w
$FC44EC-$FC4348
18,
Place graphic cursor at location
FC4172
01B4
dc .w
$FC44FC-$FC4348
19,
Remove last graphic cursor
************************************
********************
FC4174
B07C065
cmp.w
#$65, DO
VDI
ESC 101 ?
FC4178
67 OA
beq
$FC4 17 8
Yes
FC417A
B07C0066
cmp.w
#$66, DO
VDI
ESC 102 ?
FC417E
6700096A
beq
$FC4AEA
Yes
, select font
FC4182
4E75
rts
******
**************************************************
VDI
ESC 101, character offset from screen start
FC4184
6100043C
bsr
$FC45C2
Cursor off
FC4188
207900002942
move . 1
$2942, A0
Address of INTIN array
FC418E
3010
move . w
(A0) , DO
INTIN [ 0 ] , offset in raster lines
FC4190
C0F900002 93C
mulu .w
$2 93C, DO
times bytes per screen line
FC4196
33C000002 91C
move . w
DO, $2 91C
equals offset in bytes
FC419C
60000412
bra
$FC45B0
Turn cursor on again
******
**************************************************
ascout
FC41A0
322FOOO 6
move . w
6 (A7 ) ,D1
Get
character from stack
Abacus Software Atari ST Internals
FC41A4 024100FF and.w #$FF,D1
FC41A8 600005D2 bra SFC477C
********************************************************
FC41AC 322F0006 move.w 6(A7),D1
FC41B0 024100FF and.w #$FF,D1
FC41B4 2 07 9000004 A8 move . 1 $4A8,A0
FC41BA 4ED0 jmp (AO)
4^
OJ
U>
********************************************************
FC41EE
0000
dc .w
$FC4 1FE-$FC4 1FE
FC41F0
01 AC
dc .w
$FC43AA-$FC41FE
FC41F2
0004
dc .w
$FC4202-$FC41FE
FC41F4
049E
dc .w
$FC4 6 9C-$FC41FE
**************************
FC41BC B27C0020
FC41C0 6C0005BA
FC41C4 B23C001B
FC41C8 660C
cmp . w
bge
cmp . b
bne
#$20, D1
$FC477C
#$1B,D1
$FC4 1D6
FC41CA 23FCOOFC4218000004A8 move . 1 #$FC4218, $4A8
FC41D4 4E75 rts
********************************************************
FC41D6 5F4 1
FC41D8 6B22
FC41DA B27C0006
FC41DE 6E1C
FC41E0 E34 9
FC41E2 307B100A
FC41E6 D1FC00FC4 1FE
FC41EC 4ED0
subq.w #7,D1
bmi $FC4 1FC
cmp.w #6,D1
bgt $FC4 1FC
lsl.w #1 , D1
move.w $FC4 1EE (PC, D1 . w) , A0
add. 1 #$FC4 1FE, A0
Bits 0-7
Output character
conout
Character from stack
Bits 0-7
con_state vector
Execute routine
Standard conout
Control code ?
No, output character
ESC ?
No, different control codes
con_state to ESC processing
Process CTRL codes
Less than 7 ?
ignore
Greater than 13 ?
ignore
as word index
Get relative address from table
Add base address
Execute routine
Jump table for CTRL codes
7, BEL
8, BS
9, TAB
10, LF
Abacus Software Atari ST Internals
434
FC41F6
0 4 9E
dc .w
$FC4 69C-$FC41FE
11, VT
FC41F8
049E
dc . w
$FC469C-$FC41FE
12, FF
FC41FA
0492
dc .w
$FC4 690-$FC41FE
13, CR
ie ie i( -k ~k ~k *
A********************
FC41FC
4E75
rts
rts for dummy routine
***************************
***★*★*★★★★★★★★*■*•**★★
BEL
FC41FE
6000DE1C
bra
$FC201C
Output sound
***************************
★*★★*********★*★*★*★*
TAB
FC4202
303900002 91E
move . w
$291E, DO
Current cursor column
FC4208
0240FFF8
and.w
#$FFF8 , DO
Convert to number divisable by 8
FC420C
5040
addq . w
#8, DO
plus 8
FC420E
323900002920
move . w
$2920, D1
Current cursor line
FC4214
60000764
bra
$FC4 97A
Reposition cursor
***************************
****★★★★
*********************
Process character as ESC
FC4218
23FCOOFC41BCOOOOQ4A8
move . 1
#$FC4 1BC, $4 A8
con state back to standard
FC4222
927C0041
sub . w
#$41,D1
minus 'A'
FC4226
6BD4
bmi
$FC4 1FC
less, ignore
FC4228
B27COOOC
cmp . w
#$C,D1
' M '
FC422C
6F50
ble
SFC427E
To escape table for uppercase letters
FC422E
B27C0018
cmp . w
#$18, D1
'Y' for set cursor?
FC4232
663C
bne
$FC4270
No, test for lowercase letters
FC4234
23FCOOFC4240000004A8
move . 1
#$FC4240, $4 A8
con state for ESC Y
FC423E
4E75
rts
* ★ * * * ★ •*
f********************
***★*★*★
Process line under ESC Y
FC4240
927C0020
sub . w
#$20, D1
Subtract offset
FC4244
33C1000004AC
move . w
Dl, $4AC
save row, save line
Abacus Software Atari ST Internals
435
FC424A 2 3FC00FC4 2 56000004A8 move . 1 #$FC4256, $4A8
FC4254 4E75 rts
★ ★★★★A-****-************
FC4256 927C0020 sub.w #$20, D1
FC425A 3001 move.w D1,D0
FC425C 32 3 9000004 AC move.w $4AC,D1
FC4262 23FO00FC41BC000004A8 move . 1 #$FC41BC, $4A8
FC426C 6000070C bra $FC497A
*******************
FC4270 927C0021
FC4274 6B86
FC4276 B27C0015
FC427A 6F10
FC427C 4E75
*************************************
sub.w #$21, D1
bmi $FC4 1FC
cmp.w #$15, D1
ble $FC428C
FC427E E34 9
FC4280 307B1058
FC4284 D1FC00FC4 1FC
FC428A 4ED0
lsl.w #1,D1
move.w $FC42DA(PC,Dl.w) , A0
add. 1 #$FC4 1FC, A0
imp (A0)
********************************************************
FC428C E34 9 lsl.w #1,D1
FC428E 307B1064 move.w $FC42F4 (PC, D1 . w) , A0
FC4292 D1FC00FC4 1FC add.l #$FC41FC,A0
FC4298 4ED0 jmp (AO)
********************************************************
FC429A 23FC00FC42A6000004A8 move . 1 #$FC42A6, $4A8
FC42A4 4E75 rts
con_state to column process
Process column under ESC Y
Subtract offset
Column
save_row, line
con_state to standard
Set cursor
Test for ESC lowercase letters
Subtract offset
less than 'b' ignore
'w'
less than or equal, process sequence
ESC uppercase letters
Word access
Get relative address from table
Add base address
Execute routine
ESC lowercase letters
Word access
Get relative address from table
Add base address
Execute routine
ESC b, set type color
Set con state
Abacus Software Atari ST Internals
436
**********★**★■*■*★****★★★**★★'*****■*'****★******★**********
FC42A6 23FC00FC41BC000004A8 move . 1 #$FC41BC, $4A8
FC42B0 927C0020 sub.w #$20, D1
FC42B4 3001 move.w D1,D0
FC42B6 60000290 bra $FC4548
*★**★★***★******★*★**★*****★*********★*★**★★■!*:**★★★*★****
FC42BA 23FC00FC42C6000004A8 move . 1 #$FC42C6, $4A8
FC42C4 4E75 rts
********************************************************
FC42C6 23FC00FC41BC000004A8 move . 1 #$FC4 1BC, $4A8
FC42D0 927C0020 sub.w #$20, D1
FC42D4 3001 move.w D1,D0
FC42D6 6000027C bra $FC4554
FC42DA
FC42DC
FC42DE
FC42E0
FC42E2
FC42E4
FC42E6
FC42E8
FC42EA
FC42EC
FC42EE
FC42F0
FC42F2
$FC4362-
$FC437 6-
$FC4390-
$FC43AA-
$FC435E-
$FC4 1FC-
$FC4 1FC-
$FC436E-
$FC4502-
$FC43C6-
$FC43F2-
$FC451C-
$FC4538-
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
$FC4 1FC
Set type color
con_state to standard
Subtract offset
Set type color
ESC c, set background color
Set con_state
Set background color
con_state to standard
Subtract offset
Set background color
Address table for ESC uppercase
ESC A
ESC B
ESC C
ESC D
ESC E
ESC F, rts
ESC G, rts
ESC H
ESC I
ESC J
ESC K
ESC L
ESC M
Abacus Software Atari ST Internals
437
********************************************************
FC42F4 009E
FC42F6 OOBE
FC42F8 0364
FC42FA 0380
FC42FC 03C6
FC42FE 0000
FC4300 0000
FC4302 0000
FC4304 03E6
FC4306 0402
FC4308 04 1C
FC430A 0000
FC430C 0000
FC430E 043A
FC4310 029A
FC4312 02A4
FC4314 0000
FC4316 0000
FC4318 0000
FC431A 0000
FC431C 0480
FC431E 048A
***************************
FC432 0 2 07 900002 93E
FC4326 317C00020008
FC432C 207 900002 94A
FC4332 30390000290E
FC4338 5240
FC433A 31400002
FC433E 303900002910
dc.w $FC42 9A-$FC4 1FC
dc.w $FC4 2BA-$FC4 1FC
dc.w $FC4560-$FC41FC
dc.w $FC4 57C-$FC4 1FC
dc.w $FC45C2-$FC41FC
dc.w $FC4 1FC-$FC4 1FC
dc.w $FC4 1FC-$FC4 1FC
dc.w $FC41FC-$FC41FC
dc.w $FC45E2-$FC41FC
dc.w $FC45FE-$FC4 1FC
dc.w $FC4 618-$FC4 1FC
dc.w $FC4 1FC-$FC4 1FC
dc.w $FC4 1FC-$FC4 1FC
dc.w $FC4636-$FC41FC
dc.w $FC4496-$FC41FC
dc.w $FC4 4 A0-$FC4 1FC
dc.w $FC4 1FC-$FC4 1FC
dc.w $FC41FC-$FC41FC
dc.w $FC4 1FC-$FC4 1FC
dc.w $FC41FC-$FC41FC
dc.w $FC4 67C-$FC4 1FC
dc.w $FC4 68 6-$FC4 1FC
t ****************************
lea $2 93E, AO
move.w #2, 8 (AO)
move . 1 $294A,A0
move.w $290E,D0
addq.w #1,D0
move.w DO, 2 (A0)
move.w $2910, DO
Address table for ESC lowercase
ESC b
ESC c
ESC d
ESC e
ESC f
ESC g, rts
ESC h, rts
ESC i, rts
ESC j
ESC k
ESC 1
ESC m, rts
ESC n, rts
ESC o
ESC p
ESC q
ESC r, rts
ESC s, rts
ESC t, rts
ESC u, rts
ESC v
ESC w
VDI ESC 1, get screen size
Address of CONTRL array
2 result values
Address of INTOUT array
Maximum cursor column
plus 1 equals number of columns
as INTOUT [1]
Maximum cursor line
Abacus Software Atari ST Internals
438
FC4344 5240
FC4346 3080
FC4348 4E75
addq.w #l,DO
move . w DO, (AO)
rts
FC434A 3F3C0014
FC434E 4E4E
FC4350 548F
FC4352 4E75
move.w #$14, -(hi)
trap #14
addq.l #2,A7
FC4354 6108
FC4356 60000224
$FC435E
$FC457C
FC435A 61000266
$FC45C2
FC435E 615E
FC4360 6064
$FC4 3BE
SFC43C6
FC4362 323900002920
FC4368 67DE
FC436A 5341
FC436C 30390000291E
FC4372 60000606
move.w $2920,D1
beq $FC4348
subq.w #1,D1
move.w $291E,D0
bra $FC4 97A
FC4376 323900002920
FC437C B27900002910
FC4382 67C4
move.w $2920,D1
cmp.w $2910, D1
beq $FC4348
plus 1 equals number of lines
as INTOOT [0]
VDI ESC 17, hardcopy
Hardcopy
XBIOS
Correct stack pointer
VDI ESC 3, Enter alpha mode
ESC E, Clear home, clear screen
ESC e. Cursor on
VDI ESC 2, Exit alpha mode
ESC f. Cursor off
ESC E, Clear home
ESC H, Cursor home
ESC J, Clear rest of screen
ESC A, VDI ESC 4, Cursor up
Current cursor line
Zero, done
Subtract one
Current cursor column
Set cursor
ESC B, VDI ESC 5, Cursor down
Current cursor line
Maximum cursor line
Already in lowest line?
Abacus Software Atari ST Internals
439
FC4384
5241
addq . w
#1 , D1
Increment by one
FC 4 3 8 6
303900002 91E
move . w
$2 91E, DO
Current cursor
column
FC438C
600005EC
bra
SFC497A
Set cursor
************************************
********************
ESC C, VDI ESC
6, Cursor right
FC4390
303900002 91E
move . w
$2 91E, DO
Current cursor
column
FC4396
B07 900002 90E
cmp. w
$2 90E, DO
Maximum cursor
column
FC439C
67AA
beq
$FC4348
Already in last
. column?
FC439E
5240
addq . w
#1 , DO
Increment by one
FC43A0
323900002920
move . w
$2920, D1
Current cursor
line
FC43A6
600005D2
bra
$FC4 97A
Set cursor
**********************
**********************************
ESC D, BS, VDI
ESC 7, Cursor left
FC43AA
30390000291E
move . w
$2 91E, DO
Current cursor
column
FC43B0
6796
beq
$FC4348
Cursor already
in first column?
FC43B2
5340
subq.w
#1 , DO
Subtract one
FC43B4
323900002920
move . w
$2920, D1
Current cursor
line
FC43BA
600005BE
bra
$FC4 97A
Set cursor
********************************************************
ESC H, VDI ESC
8, Cursor home
FC43BE
7000
moveq . 1
#0, DO
Column 0
FC43C0
3200
move . w
DO, D1
Line 0
FC43C2
600005B6
bra
$FC4 97A
Set cursor
★****★'
**************************************************
ESC J, VDI ESC
9, Clear rest of s<
FC43C6
612A
bsr
$FC4 3F2
ESC K, Clear rest of line
FC43C8
323900002920
move . w
$2920, D1
Current cursor
line
FC43CE
B2 7 900002 910
cmp . w
$2910, D1
Maximum cursor
line
FC43D4
6700FF7 2
beq
$FC4348
FC43D8
5241
addq . w
#1 , D1
FC43DA
4841
swap
D1
FC43DC
323COOOO
move . w
#0, D1
A
Abacus Software Atari ST Internals
440
FC43E0 343900002910
FC43E6 4842
FC4 3E8 34 39000 02 90E
FC43EE 60000436
***************************
FC43F2 08B9000300002934
FC43FA 40E7
FC43FC 610001C4
FC4400 61O001E0
FC4404 32 3 900002 91E
FC440A 08010000
FC440E 6716
FC4410 B27 900002 90E
FC4416 673A
FC4 4 18 323C0020
FC441C 6100035E
FC4420 32390000291E
FC4426 4841
FC4428 323900002920
FC442E 3401
FC4430 4841
FC4432 4842
FC4 4 34 34 3 900002 90E
FC443A 610003EA
FC443E 4 4DF
FC4440 6708
FC4442 08F9000300002934
FC444A 610001B2
FC444E 60000160
FC4452 323C0020
FC4 456 61000324
move.w $2910, D2
swap D2
move.w $290E,D2
bra $FC4826
***************************
bclr #3, $2934
move . w SR, ~ ( A7 )
bsr $FC45C2
bsr $FC45E2
move.w $291E,D1
btst #0, D1
beq $FC4426
cmp.w $290E,D1
beq $FC4452
move.w #$20, D1
bsr $FC477C
move.w $291E,D1
swap D1
move.w $2920,D1
move.w D1,D2
swap D1
swap D2
move.w $290E,D2
bsr $FC4826
move.w (A7)+,CCR
beq $FC444A
bset #3 , $2934
bsr $FC45FE
bra $FC45B0
move.w #$20, D1
bsr $FC4 7 7C
Maximum cursor line
Maximum cursor column
Clear screen area
ESC K, VDI ESC 10, Clear rest of line
Cursorflag, clear wrap
Save old value
ESC f. Cursor off
ESC j. Store cursor position
Current cursor column
Maximum cursor column
Blank
Output
Current cursor column
Current cursor line
Maximum cursor column
Clear screen area
Restore flag
Not set?
Cursorflag, set wrap
ESC k, Restore cursor position
Turn cursor back on
Blank
output
Abacus Software Atari ST Internals
441
FC445A 60E2
bra
$FC4 4 3E
FC445C 207900002942
FC4462 3210
FC4464 5341
FC4466 30280002
FC446A 5340
FC446C 6000050C
move . 1 $2 942, AO
move . w (AO) , D1
subq.w #1,D1
move . w 2 (A0) , DO
subq.w #1,D0
bra $FC4 97A
FC4470
FC4476
FC447A
FC4480
FC4482
FC4484
FC4488
FC448C
FC4490
FC4494
207 900002 93E
30280006
207900002942
600E
3218
48E78080
6100FD2 6
4CDF0101
51C8FFF0
4E75
move . 1
move .w
move . 1
bra
move . w
movem . 1
bsr
movem. 1
dbra
$293E, A0
6 (A0) , DO
$2942, A0
$FC4 4 90
(A0) +,D1
D0/A0, -<A7)
$FC4 1B0
(A7 ) +, D0/A0
DO, $FC4482
*************************
FC4496 08F9000400002934
FC449E 4E75
bset #4, $2934
********************************************************
FC44AO 08B90004 00002 934 bclr #4, $2934
FC44A8 4E75 rts
move . 1 $293E,A0
FC44AA 20790000293E
VDI ESC 11, Set cursor
Address of the INTIN array
Get line
Subtract offset
Get column
Subtract offset
Set cursor
VDI ESC 12, Text output
Address of the CONTRL array
Number of characters
Address of the INTIN array
To end of loop
Get characters in D1
Save registers
Output character in D1
Restore registers
Output next character
ESC p, VDI ESC 13, Reverse on
Cursor flag, set reverse
ESC q, VDI ESC 14, Reverse off
Cursor flag, clear reverse
VDI ESC 15, Get cursor position
Address of the CONTRL array
Abacus Software Atari ST Internals
442
FC44B0 3 1 7C00020008 raove.w #2,8(A0)
FC44B6 2 07 900002 94 A move . 1 $294A,A0
FC44BC 303900002920 move . w $2920, DO
FC44C2 5240 addq.w #1,D0
FC44C4 3080 move.w DO, (A0)
FC44C6 30390000291E move.w $291E,D0
FC44CC 5240 addq.w #1,D0
FC44CE 31400002 move.w D0,2(A0)
FC44D2 4E75 rts
********************************************************
FC44D4 2 07 900002 93E
FC44DA 317C00010008
FC44E0 207 900002 94A
FC44E6 30BC0001
FC44EA 4E75
move . 1 $293E,A0
move.w #1,8 (A0)
move . 1 $294A,A0
move . w #1, (A0)
FC44EC 207900002942
FC44F2 30BC0000
FC44F6 4EF900FCAFCA
move.l $2942, A0
move .w #0, (A0)
imp $FCAFCA
FC44FC 4EF900FCAFF2
$FCAFF2
FC4502 323900002920
FC4508 6600FE60
FC450C 3F3 900002 91E
FC4512 6108
FC4514 301F
FC4516 7200
FC4518 60000460
move.w $2920, D1
bne $FC436A
move.w $291E,-(A7)
bsr $FC451C
move . w (A7 ) +, DO
moveq.l #0,D1
bra $FC4 97A
2 result values
Address of the INTOUT array
Current cursor line
plus offset
as INTOUT [0]
Current cursor column
plus offset
as INTOUT [1]
VDI ESC 16, Inquire tablet status
Address of CONTRL array
One result value
Address of the INTOUT array
Tablet available
VDI ESC 18, Set graphic cursor
Address of the INTIN array
No result value
Turn mouse cursor off
VDI ESC 19, Clear graphic cursor
Turn mouse cursor off
ESC I, Cursor up, scroll if necessary
Current cursor line
Not in line 0, cursor up
Save current cursor column
ESC L, insert line
Restore cursor column
Line 0
Set cursor
Abacus Software Atari ST Internals
443
FC451C 610000A4
FC4520 323900002920
FC4526 6100058A
FC452A 4240
FC452C 323900002920
FC4532 61000446
FC4536 6078
bsr $FC45C2
move.w $2920, D1
bsr $FC4AB2
clr.w DO
move.w $2920, D1
bsr $FC4 97A
bra $FC45B0
********************
FC4538 61000088
FC453C 323900002920
FC4542 61000526
FC4546 60E2
bsr $FC45C2
move.w $2920, D1
bsr $FC4A6A
bra $FC452A
***********
FC4548 C07C000F
FC454C 33C000002916
FC4552 4E75
and.w #$F,D0
move.w DO, $2916
***************
FC4554 C07COOOF
FC4558 33C000002 914
FC455E 4E75
and.w #$F , DO
move.w DO, $2914
********************
FC4560 610000D4
FC4564 343900002920
FC456A 67F2
FC456C 5342
FC456E 4842
*************************************
bsr $FC4636
move.w $2920, D2
beq $FC455E
subq.w #1,D2
swap D2
ESC L, Insert line
ESC f. Cursor off
Current cursor line
Scroll rest of screen down
Column 0
Current cursor line
Set cursor
Turn cursor on again
ESC M, Delete line
ESC f. Cursor off
Current cursor line
Move rest of screen up
Set background color
Color 0-15
Type color
Set background color
Color 0-15
Background color
ESC d. Clear screen to cursor
ESC o. Clear line to cursor
Current cursor line
Zero, done
Abacus Software Atari ST Internals
444
FC4570 34390000290E move.w $290E,D2
FC4576 7200 moveq . 1 #0,D1
FC4578 600002AC bra $FC4826
********************************************************
FC457C 4A7 900002 7E0
FC4582 67DA
FC4584 4279000027E0
FC458A 4 1F90 0002 93 4
FC4590 08100000
FC4594 660E
FC4596 08D00002
FC459A 227900002918
FC45A0 60000456
tst.w $27E0
beq $FC455E
clr.w $27E0
lea $2934, AO
btst #0, (AO)
bne $FC45A4
bset #2, (AO)
move . 1 $2918, A1
bra $FC4 9F8
FC45A4 61F4
FC45A6 08D00001
FC45AA 08D00002
FC45AE 4E75
$FC459A
#1, (A0)
#2, (A0)
*******************1*
FC45B0 4A79000027E0
FC45B6 67A6
FC45B8 5379000027E0
FC45BE 67CA
FC45C0 4E75
tst.w $27E0
beq $FC455E
subq.w #1,$27E0
beq $FC458A
********************
FC45C2 5279000027EO
FC45C8 4 1F900002 934
FC45CE 08900002
FC45D2 678A
FC45D4 08100000
addq.w #1, $27E0
lea $2934, A0
bclr #2, (AO)
beq $FC455E
btst #0, (AO)
Maximum cursor column
Clear screen area
ESC e. Turn cursor on
Cursor already on?
Yes, done
Clear number of hide calls
Cursor flag
Screen address of the cursor
Invert character at cursor position
Invert character at cursor position
Cursor on ?
Yes, rts
Decrement number of hide calls
Turn on again
ESC f. Cursor off
Increment number of hide calls
Cursor flag
Cursor not visible
Cursor was already off
Cursor flashing ?
Abacus Software Atari ST Internals
445
$FC459A
#1, (AO)
$FC 4 5 9A
FC45D8 67C0 beq
FC45DA 08900001 bclr
FC45DE 6 6BA bne
FC45E0 4 E7 5 rts
********************************************************
FC45E2 08F9000500002934 bset #5, $2934
FC45EA 41F9000027EC lea $27EC,A0
FC45F0 30F900002 91E move.w $291E,(A0) +
FC4 5F6 30B900002 92 0 move.w $2920, (AO)
FC45FC 4E75 rts
********************************************************
FC45FE
08B9000500002934
bclr
#5, $2934
FC4606
67 00FDB6
beq
$FC4 3BE
FC460A
4 1F900002 7EC
lea
$27EC, A0
FC4610
3018
move . w
(A0) +, DO
FC4612
3210
move . w
(A0) ,D1
FC4614
60000364
bra
$FC4 97A
**********
FC4618
61A8
bsr
$FC45C2
FC461A
323900002920
move . w
$2920, D1
FC4620
3401
move . w
D1,D2
FC4622
4841
swap
D1
FC4624
4241
clr . w
D1
FC4626
4842
swap
D2
FC4628
343900002 90E
move . w
$2 90E, D2
FC462E
610001F6
bsr
$FC4 82 6
FC4632
6000FEF6
bra
$FC452A
No
Cursor not visible
Invert character at cursor position
ESC j, Save cursor position
Cursor flag, position saved
Address of the save area
Current cursor column
Current cursor line
ESC k, Cursor to saved position
Cursor flag, position saved?
No, Cursor home
Address of the save area
Cursor column
Cursor line
Set cursor
ESC 1, Delete line
ESC f. Turn cursor off
Current cursor line
Maximum cursor column
Clear screen area
Cursor in colun zero
ESC o. Clear line to cursor
Abacus Software Atari ST Internals
446
FC4636 618A
FC4638 61A8
FC4 63A 3 4 3 900002 91E
FC4640 6730
FC4642 08020000
FC4646 6610
FC4648 323C0020
FC464C 6100012E
FC4650 34390000291E
FC4656 5542
FC4658 4842
FC465A 343900002920
FC4660 3202
FC4662 4842
FC4664 4841
FC4666 4241
FC4668 610001BC
FC466C 6190
FC466E 6000FF40
FC4672 323C0020
FC4 67 6 61000104
FC467A 60F0
bsr $FC4 5C2
bsr $FC45E2
move.w $291E,D2
beq $FC4672
btst #0,D2
bne $FC4658
move.w #$20, D1
bsr $FC477C
move.w $291E,D2
subq.w #2,D2
swap D2
move.w $2920, D2
move.w D2,D1
swap D2
swap D1
clr.w D1
bsr SFC4826
bsr $FC45FE
bra $FC45B0
move.w #$20, D1
bsr $FC477C
bra $FC466C
********************************************************
FC467C 08F9000300002934 bset #3, $2934
FC4684 4E75 rts
********************************************************
FC4686 08B9000300002934 bclr #3, $2934
FC468E 4E75 rts
ESC f. Turn cursor off
ESC j. Save cursor position
Current cursor column
Zero, done
Blank
output
Current cursor column
Current cursor line
Clear screen area
ESC k, Cursor to saved position
and turn cursor back on
Blank
output
ESC v. Turn line-wrap off
Cursor flag, flag for new line
ESC w. Turn line-wrap on
Cursor flag, clear flag
CR, Cursor to column zero
447
Current cursor line
Column zero
Set cursor
LF, (VT, FF) , Cursor down
Current cursor line
Maximum cursor line
Not in lowest line, just cursor down
ESC f. Turn cursor off
Scroll screen up
and turn cursor back on
Flash cursor
Cursor flag
Update flag set ?
Yes, do nothing
Cursor turned on ?
No
Cursor flashing ?
No
Cursor flash counter
decrement
Run out?
Reload cursor flash rate
Invert cursor phase
Screen address of the cursor
Invert character at cursor position
Cursor configuration
Function number
Abacus Software Atari ST Internals
448
FC4 6F 6
6BF8
bmi
$FC46F0
Negative, ignore
FC46F8
B07C0005
cmp . w
#5, DO
Greater than 5 ?
FC4 6FC
6EF2
bgt
$FC4 6F0
Yes
FC46FE
E340
asl . w
#1 , DO
Word access
FC4700
4 1F90 0FC4 7 1 8
lea
$FC4 718, AO
Base address of the table
FC4706
D0FB0004
add. w
$FC4 7 OC (PC, DO . w) , AO
plus relative address
FC470A
4ED0
jmp
(AO)
Execute routine
********************************************************
Jump
table for cursor configuration
FC470C 0000
dc .w
$FC4718-$FC4718
FC470E 0004
dc .w
$FC471C-$FC4718
FC4710 0008
dc .w
$FC4720-$FC4718
FC4712 0016
dc .w
$FC472E-$FC4718
FC4714 0024
dc ,w
$FC473C-$FC4718
FC4716 002C
dc .w
$FC4744-$FC4718
**********************
***********************************
0
FC4718 6000FEA8
bra
SFC45C2
ESC
f, Turn
cursor
on
*********************************************************
1
FC471C 6000FE5E
bra
$FC457C
ESC
e. Turn
cursor
on
*********************************************************
2
FC4720 6100FEA0
bsr
$FC45C2
ESC
f. Turn
cursor
off
FC4724 08ED00002 934
bset
#0 , $2934 (A5)
Cursor flag
FC472A 6000FE84
bra
$FC4 5B0
And
back on
********************************************************
3
FC472E 6100FE92
bsr
$FC45C2
ESC
f. Turn
cursor
off
FC4732 08AD00002 934
bclr
#0, $2934 ( A5 )
Cursor flag
FC4738 6000FE7 6
bra
$FC45B0
And
back on
Abacus Software Atari ST Internals
449
FC473C 1B6F00072922
FC4742 4E75
move . b 7 ( A7 ) , $2 922 ( A5)
rts
************************
********************************
FC4744
7000
moveq . 1
#0 , DO
FC4746
102D2922
move . b
$2922 (A5) , DO
FC474A
4E75
rts
************************************
********************
FC474C
3 63 900002 92A
move . w
$2 92 A, D3
FC4752
B2 4 3
cmp . w
D3,D1
FC4754
6522
bcs
$FC4778
FC4756
B27900002928
cmp . w
$2928, D1
FC475C
62 1A
bhi
$FC4778
FC475E
207900002930
move . 1
$2930, A0
FC4764
D241
add.w
D1,D1
FC4766
32301000
move . w
0 (A0, D1 . w) ,D1
FC476A
E64 9
lsr .w
#3, D1
FC476C
207900002924
move . 1
$2 92 4, A0
FC4772
D0C1
add.w
D1 , A0
FC4774
4243
clr .w
D3
FC4776
4E75
rts
FC4778
7601
moveq . 1
#1 , D3
FC477A
4E7 5
rts
********************************************************
FC477C
61CE
bsr
$FC4 7 4C
FC477E
6702
beq
$FC4782
FC4780
4E7 5
rts
FC4782
227900002918
move . 1
$2918, A1
FC4788
3E3900002914
move . w
$2914, D7
Set cursor flash rate
5
Load cursor flash rate
Calculate font data for character in D1
Smallest ASCII code in font
Compare with character to output
Character not in font
Largest ASCII code in font
Character not in font
Pointer to offset data
Code times 2
Yields bit number in font
Divided by 8 equals byte number
Pointer to font data
Yields pointer to data for this character
Flag for character present
Character not in font
ascout, ignore control codes
Character in font?
Yes
Screen address of the cursor
Background color
Abacus Software Atari ST Internals
450
FC478E 4847
FC4790 3E3 900002 91 6
FC4796 0839000400002934
FC479E 6702
FC47A0 4847
FC47A2 08B90002 00002 934
FC47AA 4 0E7
FC47AC 61000160
FC47B0 227900002918
FC4 7B6 303900002 91E
FC47BC 323900002920
FC47C2 610002 6E
FC47C6 6732
FC47C8 303900002912
FC47CE C0C1
FC47D0 227 90000044E
FC47D6 D3C0
FC47D8 4240
FC47DA B27900002910
FC47E0 640A
FC47E2 D2F900002912
FC47E8 5241
FC47EA 600E
FC47EC 48E7C040
FC47FO 7200
FC47F2 61000276
FC47F6 4CDF0203
FC47FA 23C900002918
FC4800 33C000002 91E
FC4806 33C100002920
FC480C 4 4DF
FC480E 6714
swap D7
move.w $2916,D7
btst #4, $2934
beq $FC4 7A2
swap D7
bclr #2, $2934
move.w SR, -(A7)
bsr $FC4 90E
move.l $2918, A1
move.w $291E,D0
move.w $2920, D1
bsr $FC4A32
beq $FC4 7FA
move.w $2912,00
mulu.w D1 , DO
move.l $44E,A1
add.l D0,A1
clr.w DO
cmp.w $2910, D1
bcc $FC4 7EC
add.w $2912,A1
addq.w #1,D1
bra $FC4 7FA
movem.l D0-D1/A1 , - ( A7)
moveq.l #0,D1
bsr $FC4A6A
movem.l (A7) +, D0-D1/A1
move.l Al,$2918
move.w D0,$291E
move.w Dl,$2920
move.w (A7)+,CCR
beq $FC4 82 4
In upper word
Type color in lower word
Cursor flag, reverse ?
No
Exchange colors
Cursor flag, character in flash phase?
Save status
Write character to the screen
Screen address of the cursor
Current cursor column
Current cursor line
Increment cursor position
No CR/LF needed ?
Bytes per character line
times lines
_v_bs_ad
yields address of the character
Column 0
Cursor in lowest line?
Yes
Bytes per character line, next line
Increment line
Save registers
to line 0
Scroll screen up
Restore registers
Screen address of the cursor
Current cursor column
Current cursor line
Restore status
Flag not set?
Abacus Software Atari ST Internals
5FC49F8
#1, $2934
#2,52934
Invert character at cursor position
Cursor flag, cursor visible
Cursor flag, cursor in flash phase
Clear screen area
Cursor column
Cursor line
Calculate cursor position
Number of screen planes
Low resolution ?
No
minus 1, yields 1, 2, 3
Number of bytes per screen line
times height of a character
als dbra counter
Background color
Number of screen planes
High resolution ?
Medium resolution ?
Low resolution
Background color, bit 0 into carry
Abacus Software Atari ST Internals
452
negx . w
swap
asr . w
negx . w
clr . 1
asr . w
negx . w
swap
asr . w
negx . w
move . w
move . 1
move . 1
dbra
add. 1
dbra
rts
DO
DO
#1 , D5
DO
D3
#1 , D5
D3
D3
#1, D5
D3
D1,D5
DO, (Al) +
D3, (Al) +
D5, $FC4888
A2 , Al
D2, $FC4886
FC4898
E245
asr.w
#1 , D5
FC489A
4040
negx . w
DO
FC489C
4840
swap
DO
FC489E
E245
asr.w
#1 , D5
FC48A0
4040
negx . w
DO
FC48A2
3A01
move . w
D1,D5
FC48A4
22C0
move . 1
DO, ( Al ) +
FC48A6
51CDFFFC
dbra
D5, $FC48A4
FC48AA
D3CA
add. 1
A2, Al
FC48AC
51CAFFF4
dbra
D2 , $FC48A2
FC48B0
4E7 5
rts
Bit set, invert word
Background color, bit 1 into color
Bit set, invert word
Planes three and four
Background color, bit 2 into carry
Bit set, invert word
Background color, bit 3 into carry
Bit set, invert word
Number of long words per line
Color planes one and two
Color planes three and four
Next long word
Pointer to next raster line
Next raster line
Medium resolution
Background color, bit 0 into carry
Bit set, invert word
Background color, bit 1 into carry
Bit set, invert word
Number of long words per line
Color planes one and two
Next long word
Pointer to next raster line
Next raster line
Abacus Software Atari ST Internals
453
********************************************************
FC48B2 E245
FC48B4 4040
FC48B6 3A01
FC48B8 32C0
FC48BA 51CDFFFC
FC48BE D3CA
FC48C0 51CAFFF4
FC48C4 4E75
***************************’
FC48C6 363900002 90E
FC48CC B64 0
FC48CE 6A02
FC48D0 3003
FC48D2 363900002910
FC48D8 B64 1
FC48DA 6A02
FC48DC 3203
FC48DE 36390000293A
FC48E4 3AOO
FC48E6 08850000
FC48EA C6C5
FC48EC 08000000
FC48F0 6702
FC48F2 5283
FC48F4 3A3900002912
FC48FA CAC1
FC48FC 227 9000004 4E
FC4902 D3C5
FC4904 D3C3
FC4906 D2F90000291C
asr . w #1 , D5
negx.w DO
move.w D1,D5
move . w DO, (Al) +
dbra D5,$FC48B8
add.l A2,A1
dbra D2,$FC48B6
rts
k****************************
move.w $290E,D3
cmp.w D0,D3
bpl $FC48D2
move.w D3,D0
move.w $2910, D3
cmp.w D1,D3
bpl $FC48DE
move.w D3,D1
move.w $293A,D3
move.w D0,D5
bclr #0,D5
mulu.w D5,D3
btst #0,D0
beq $FC48F4
addq.l #1,D3
move.w $2912, D5
mulu.w D1,D5
move . 1 $44E,A1
add.l D5,A1
add.l D3,A1
add.w $291C,A1
high resolution
Background color, bit 0 in carry
Bit set, invert word
Number of long words per line
Color plane one
Next long word
Pointer to next raster line
Next raster line
Calculate cursor position (D0/D1)
Maximum cursor column
Column value too large?
No
Replace with maximum value
Maximum cursor line
Line value too large?
No
Replace with maximum value
Number of screen planes
Column
Round to even value
Number of screen planes times cursor column
Odd column?
No
Add one
Bytes per character line
Times cursor line
_v_bs_ad
plus line offset
plus column offset
plus offset from screen start
Abacus Software Atari ST Internals
454
FC490C 4E75
rts
FC490E
347 900002 92C
move . w
$2 92C, A2
FC4914
3 67 900002 93C
move . w
$293C, A3
FC491A
38390000290C
move . w
$2 90C, D4
FC4920
5344
subq . w
#1, D4
FC4922
3C3 900002 93A
move . w
$2 93A, D6
FC4928
5346
subq . w
#1, D6
FC492A
3A04
move . w
D4,D5
FC492C
2848
move . 1
A0, A4
FC492E
2A4 9
move . 1
Al, A5
FC4930
E287
asr . 1
#1, D7
FC4932
0807000F
btst
#15, D7
FC4936
6706
beq
$FC4 93E
FC4938
642A
bcc
$FC4 964
FC493A
7 6FF
moveq . 1
#-l, D3
FC493C
6004
bra
$FC4 942
FC493E
6512
bcs
$FC4 952
FC4940
7600
moveq . 1
#0, D3
FC4942
1A83
move . b
D3, (A5)
FC4944
DACB
add.w
A3, A5
FC4946
51CDFFFA
dbra
D5, $FC4 942
FC494A
5449
addq . w
#2, Al
FC494C
51CEFFDC
dbra
D6, $FC492A
FC4950
4E75
rts
**********************-**********************************
FC4952 1A94 move.b (A4),(A5)
FC4954 DACB add.w A3,A5
FC4956 D8CA add.w A2,A4
Character from font on the screen
Width of font, formwidth
Number of bytes per screen line
Height of a character
as dbra counter
Number of screen planes
as dbra counter
Counter for raster lines
Font address of the character
Screen address of the character
Next bit back- and foreground color
Bit set in background color?
No
Foreground color not set?
Fore- and background colors set
Foreground color set?
Fore and background cleared
Set byte in video RAM
Pointer to next raster line
Next raster line
Pointer to next color plane
Next color plane
Set foreground color only
Copy byte in font in video RAM
Next raster line of the screen
Next raster line in font
Abacus Software Atari ST Internals
FC4958 51CDFFF8
FC495C 5449
FC495E 51CEFFCA
FC4962 4E75
dbra D5,$FC4952
addq.w #2,A1
dbra D6,$FC492A
FC4964 1614
FC4966 4603
FC4968 1A83
FC496A DACB
FC496C D8CA
FC496E 51CDFFF4
FC4 97 2 5449
FC4 97 4 51CEFFB4
FC4978 4E75
move . b (A4 ) , D3
not.b D3
move . b D3 , ( A5)
add.w A3,A5
add.w A2,A4
dbra D5,$FC4964
addq.w #2,A1
dbra D6,$FC492A
FC497A B07 900002 90E
FC4980 6306
FC4982 30390000290E
FC 4 9 8 8 B27 900002 910
FC498E 6306
FC4990 323900002910
FC4996 33C000002 91E
FC499C 33C100002920
FC49A2 41F900002934
FC49A8 08100002
FC49AC 673E
FC49AE 08100000
FC49B2 670A
FC49B4 08900002
FC49B8 08100001
cmp.w
bis
move . w
cmp.w
bis
$2 90E, DO
$FC4 988
$2 90E, DO
$2910, D1
$FC4 996
$2910, D1
DO , $2 91E
D1 , $2920
$2934, A0
#2, (A0)
$FC4 9EC
#0, (A0)
$FC4 9BE
#2, (A0)
#1, (AO)
Write next raster line
Pointer to next color plane
Next color plane
Set background color only
Get byte from font
Invert
and to screen
Next raster line on the screen
Next raster line in font
Display next raster line
Pointer to next color plane
Next color plane
Set cursor
Compare column with maximum value
Smaller ?
Maximum cursor column
Compare line with maximum value
Smaller ?
Maximum cursor line
Current cursor column
Current cursor line
Cursor flag
Cursor in flash phase?
No
Cursor flashing ?
No
Clear flag for flash phase
Cursor visible ?
Abacus Software Atari ST Internals
456
FC49BC
67 IE
beq
SFC49DC
FC49BE
227900002918
move . 1
$2918, A1
FC4 9C4
6132
bsr
3FC49F8
FC49C6
6100FEFE
bsr
$FC48C6
FC49CA
23C900002918
move . 1
Al, $2918
FC49D0
6126
bsr
$FC4 9F8
FC49D2
08F9000200002934
bset
#2, $2934
FC49DA
4E75
rts
FC49DC
6100FEE8
bsr
$FC48C6
FC49E0
23C900002 918
move . 1
Al, $2918
FC49E6
08D00002
bset
#2, (AO)
FC49EA
4E75
rts
FC49EC
6100FED8
bsr
$FC48C6
FC49F0
23C900002 918
move . 1
Al, $2918
FC49F6
4E75
rts
FC49F8
34 7 900002 93C
move . w
$2 93C, A2
FC49FE
383900002 90C
move . w
$2 90C, D4
FC4A04
5344
subq . w
#1, D4
FC4A06
3C390000293A
move . w
$2 93A, D6
FC4A0C
5346
subq.w
#1, D6
FC4A0E
08F9000600002934
bset
#6, $2934
FC4A16
3A04
move . w
D4 , D5
FC4A18
2849
move . 1
Al, A4
FC4A1A
4614
not .b
(A4 )
FC4A1C
D8CA
add . w
A2 , A4
FC4A1E
5 1CDFFFA
dbra
D5 , $FC4A1A
FC4A22
5449
addq . w
#2 , Al
FC4A24
51CEFFF0
dbra
D6, $FC4A1 6
FC4A28
08B9000600002934
bclr
#6, $2934
FC4A30
4E75
rts
No
Screen address of the old cursor
Invert character at cursor position
Calculate new cursor position
Screen address of the new cursor
Invert character at cursor position
Cursor flag
Calculate cursor position
Screen address of the cursor
Cursor in flash phase
Calculate cursor position
Screen addres of the cursor
Invert character at cursor position
Number of bytes per screen line
Height of a character
as dbra counter
Number of screen planes
as dbra as counter
Set cursor flag for update
Counter for raster lines
Screen address of the cursor
Invert byte
Pointer to next raster line
Next raster line
Pointer to next color plane
Next color plane
Clear cursor flag for update
Abacus Software Atari ST Internals
457
FC4A32
B07 900002 90E
cmp . w
$290E, DO
FC4A38
6612
bne
$FC4A4C
FC4A3A
0839000300002934
btst
#3, $2934
FC4A42
6604
bne
$FC4A48
FC4A44
4243
clr .w
D3
FC4A46
4E7 5
rts
FC4A48
7601
moveq . 1
#1, D3
FC4A4A
4E75
rts
FC4A4C
5240
addq . w
#1 , DO
FC4A4E
08000000
btst
#0, DO
FC4A52
6706
beq
$FC4A5A
FC4A54
5249
addq . w
#1 , A1
FC4A56
4243
clr .w
D3
FC4A58
4E7 5
rts
FC4A5A
36390000293A
move . w
$2 93A, D3
FC4A60
E343
asl ,w
#1 , D3
FC4A62
5343
subq.w
#1, D3
FC4A64
D2C3
add.w
D3,A1
FC4A66
4243
clr .w
D3
FC4A68
4E75
rts
********************************************’
FC4A6A
2 67 90000044E
move . 1
$44E, A3
FC4A70
363900002912
move . w
$2912, D3
FC4A76
C6C1
mulu .w
D1,D3
FC4A78
47F33000
lea
0 ( A3 , D3 . '
FC4A7C
4441
neg.w
D1
FC4A7E
D27900002910
add.w
$2910, D1
Increment cursor position (D0/D1)
Cursor in last column?
No
Cursor flag, overflow in next line?
Yes
Cursor still in same line
CR/LF necessary
Next column
Even column number?
Yes, not in same word
Increment addres by one
Cursor still in same line
Number of screen planes
times 2
minus 1
Address of next position
Cursor still in same line
Scroll screen up at line D1
v_bs_ad
Bytes per character line
multiply by number of lines
Address of the current line
Current line
Maximum cursor line - current line
Abacus Software Atari ST Internals
458
FC4A84
363900002912
move . w
$2912, D3
FC4A8A
45F33000
lea
0 (A3,D3.w) ,A2
FC4A8E
C6C1
mulu . w
Dl, D3
FC4A90
E443
asr . w
#2 , D3
FC4A92
6002
bra
$FC4A96
FC4A94
2 6DA
move . 1
(A2)+, (A3) +
FC4A96
51CBFFFC
dbra
D3, $FC4A94
FC4A9A
323900002910
move . w
$2910, Dl
FC4AA0
3401
move . w
Dl , D2
FC4AA2
4841
swap
Dl
FC4AA4
4842
swap
D2
FC4AA6
4241
clr . w
Dl
FC4AA8
34390000290E
move . w
$2 90E, D2
FC4AAE
6000FD7 6
bra
$FC4 82 6
FC4AB2
26790000044E
move . 1
$44E, A3
FC4AB8
363900002910
move . w
$2910, D3
FC4ABE
C6F900002 912
mulu . w
$2912, D3
FC4AC4
4 7F33000
lea
0 (A3, D3 . w) , A3
FC4AC8
363900002912
move . w
$2912, D3
FC4ACE
45F33000
lea
0(A3,D3.w) ,A2
FC4AD2
3001
move . w
Dl, DO
FC4AD4
4440
neg.w
DO
FC4AD6
D07900002910
add.w
$2910, DO
FC4ADC
C6C0
mulu . w
DO, D3
FC4ADE
E443
asr.w
#2 , D3
FC4AE0
6002
bra
$FC4AE4
FC4AE2
2523
move . 1
- (A3) , - (A2 )
FC4AE4
51CBFFFC
dbra
D3, $FC4AE2
FC4AE8
60B6
bra
$FC4 AA0
Bytes per character line
Address of the last line
Number of bytes to move
Divided by four, equals number of longs
Copy screen lines
Next long word
Maximum cursor line
Maximum cursor column
Clear last line
****** Scroll screen down at line D1
_v_bs_ad
Maximum cursor line
Bytes per character line
Address of the last line
Bytes per character line
Address of the first line
Current line
Maximum cursor line
times bytes per character line
Divided by 4 for long word counter
Copy screen lines
Next long word
Clear top line
Abacus Software Atari ST Internals
459
FC4AEA 207900002942
FC4AF0 2050
FC4AF2 30280052
FC4AF6 33C000002 90C
FC4AFC 32390000293C
FC4B02 C2C0
FC4B04 33C100002912
FC4B0A 7200
FC4B0C 323900002936
FC4B12 82C0
FC4B14 5341
FC4B16 33C100002 910
FC4B1C 7200
FC4B1E 32390000292E
FC4B24 82E80034
FC4B28 5341
FC4B2A 33C10000290E
FC4B30 33E8 005000002 92C
FC4B38 33E800240000292A
FC4B40 33E8 002 600002 92 8
FC4B48 23E8004C00002924
FC4B50 23E8004800002930
FC4B58 4E75
move.l $2 942, AO
move . 1 (AO ) , AO
move . w 82 (A0), DO
move . w DO, $290C
move.w $293C, D1
mulu.w D0,D1
move . w D1 , $2912
moveq.l #0,D1
move.w $2936, D1
divu.w DO , D1
subq.w #1 , D1
move . w D1 , $2 910
moveq.l #0,D1
move.w $292E,D1
divu . w 52 (A0) , D1
subq.w #1,D1
move.w D1,$290E
move.w 80(A0),$292C
move.w 36(A0),$292A
move.w 38 (A0), $2928
move.l 7 6 (A0) ,$2 924
move.l 72 (A0), $2 930
rts
FCA7C4
10390000044C
move . b
$4 4C, DO
FCA7CA
C07C0003
and. w
#3, DO
FCA7CE
B07C0003
cmp. w
#3, DO
FCA7D2
6604
bne
$FCA7D8
FCA7D4
303C0002
move . w
#2, DO
FCA7D8
3F00
move . w
DO , - (A7 )
VDI ESC 102, Initialize font parameters
Address of INTIN array
Address of the font header
formhight, height of a character
save
Number of bytes per screen line
times height of a character
yields bytes per character line
Screen height in bits
Divided by font height
minus 1
yields maximum cursor line
Screen width in bits
Divide by maximum character width
minus 1
yields maximum cursor column
Width of the font, formwidth
Smallest ASCII code in font
Largest ASCII code in font
Pointer to font data
Pointer to offset data
Initialize screen output
sshiftmd, screen resolution
Isolate bits 0 and 1
3 ?
No
Replace with 2 (high resolution)
Save resolution
Abacus Software Atari ST Eternals
460
FCA7DA
61 00007E
bsr
$FCA85A
FCA7DE
301F
move . w
( A7 ) + , DO
FCA7E0
4 1F900FD2D00
lea
$FD2D00, A0
FCA7E6
B07C0002
cmp. w
#2, DO
FCA7EA
6606
bne
5FCA7F2
FCA7EC
4 1F900FD375C
lea
$FD375C, A0
FCA7F2
6100A2FE
bsr
$FC4AF2
FCA7F6
33FCFFFF00002 916
move . w
#$FFFF, $2916
FCA7FE
7000
moveq. 1
#0, DO
FCA800
33C000002 914
move .w
DO, $2914
FCA806
33C000002 91E
move . w
DO, $291E
FCA80C
33C000002920
move . w
DO, $2920
FCA812
33C000002 91C
move .w
DO, $2 91C
FCA818
207 9000004 4E
move . 1
$44E, A0
FCA81E
2 3C800002 918
move . 1
A0, $2918
FCA824
13FC 000100002 934
move .b
#1, $2934
FCA82C
13FC001E00002923
move . b
#$1E, $2923
FCA834
13FC001E00002922
move . b
#$1E, $2922
FCA83C
33FC0001000027EO
move . w
#1, $27E0
FCA844
323C1F3F
move . w
#$ 1F3F, D1
FCA848
2 0C0
move . 1
DO, (AO ) +
FCA84A
51C9FFFC
dbra
D1 , $FCA8 4 8
FCA84E
23FCOOFC41BCOOOOQ4A8
move . 1
#$FC4 1BC, $4A8
FCA858 4E75 rts
FCA85A
7200
moveq. 1
#0, D1
FCA85C
123B0030
move . b
$FCA88E (PC, DO
FCA860
33C1 0 0002 93A
move . w
D1 , $2 93A
FCA866
123B002 9
move . b
$FCA8 91 (PC, DO
FCA86A
33C10000293C
move . w
D1 , $2 93C
FCA870
33C1 0 0002 938
move . w
D1 , $2938
Set parameters for screen resolution
Restore resolution
Address of the 8x8 system-font header
High resolution ?
No
Else address of the 8x16 system-font header
Initialize font data
Type color to black
Background color white
Cursor column zero
Cursor line zero
Line offset zero
_v_bs_ad, screen address
as cursor address
Set cursor flag
Cursor flash counter to 30
Cursor flash rate to 30
Cursor not visible
8000 long words
Clear screen
constate vector to standard
Set parameters for screen resolution
Get number of screen planes
and save
Get bytes per screen line
and save
Abacus Software Atari ST Internals
FCA876
E340
asl . w
#1 , DO
FCA878
323B001A
move . w
$FCA8 94 (PC, DO . w) ,D1
FCA87C
33C1 00002 936
move . w
Dl, $2936
FCA882
323B0016
move . w
$FCA89A(PC,D0.w) ,D1
FCA886
33C1 00002 92E
move . w
Dl, $2 92E
FCA88C
4E75
rts
dc .b 4,2,1
dc.b 160,160,80
dc .w 200,200,400
dc.w 320,640,640
as
FCA88E 040201
FCA891 AOA050
FCA894 00C800C80190
FCA89A 014002800280
Resolution as word index
Get screen height
and save
Get screen width
and save
Screen parameters
Number of screen planes
Number of bytes per screen line
Screen height
Screen width
Abacus Software Alari ST Inttrnals
Chapter Four
Appendix
4.1 The System Fonts
4.2 Alphabetical listing of GEMDOS functions
Abacus Software
Atari ST Internals
4.1 The System Fonts
The operating system contains three different fonts for character output.
The 6x6 font is used by the icons, the 8x8 font is used as the standard
output on a color monitor, and the 8x16 font is used for the monochrome
monitor output. The chart on the next page includes the characters with the
ASCII codes 1 to 255.
465
Abacus Software
Atari ST Internals
6X6 System Font 8X8 System Font 8X16 System Font
0.
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466
Abacus Software
Atari ST Internals
4.2 Alphabetical listing of GEMDOS functions
Name
Opcode (hex)
Page Number
Cauxin
03
108
Cauxis
12
115
Cauxos
13
115
Cauxout
04
109
Cconin
01
107
Cconis
OB
113
Cconos
10
1 14
Cconout
02
108
Cconrs
0A
112
Cconws
09
111
Cnee in
08
111
Cpmos
11
115
Cpmout
05
109
Crawcin
07
110
Crawio
06
110
Dcreate
39
123
Ddelete
3A
124
Dfree
36
122
Dgetdrv
19
116
Dgetpath
47
135
Dsetdrv
0E
114
Dsetpath
3B
125
Fattrib
43
132
Fclose
3E
128
Fcreate
3C
126
Fdatime
57
143
Fdelete
41
130
Fdup
45
134
Fforce
46
134
Fgetdta
2F
120
Fopen
3D
127
Fread
3F
129
Frename
56
143
Fseek
42
131
Fsetdta
1A
116
Fsfirst
4E
140
Fsnext
4F
142
Fwrite
40
130
467
Abacus Software
Atari ST Internals
Malloc
48
135
Mfree
49
137
Mshrink
4A
137
Pexec
4B
138
Pterm
4C
140
PtermO
00
107
Ptermres
31
121
Super
20
117
Sversion
30
121
Tgetdate
2A
118
Tgettime
2C
119
Tsetdate
2B
119
Tsettime
2D
120
468
Abacus Software
Atari ST Internals
4.3 The blitter chip
Anyone who has followed the development of the ST has surely heard the
word blitter. More than two years were spent developing the blitter chip.
The main advantage of this chip is its speed, working with data in the DMA
register. The blitter uses a memory range independent of the 68000
microprocessor. Without the blitter chip, you need several kilobytes of
program code to realize graphics through software.
The basic graphic routines of the ST are accessed by software through
line-A opcodes. The blitter can take on parts of these routines and execute
them faster than the 68000 could handle them. That is first taken by the
BITBLT function, shifting the established pixel-oriented memory range.
However, the fill can be taken up in any memory range. The details of the
blitter options follow later. First let's look at chip design.
Figure 4.3-1 BLITTER
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D 14
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A 23
A 22
A 21
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A 20
A 19
A 18
A 17
A 16
A 15
A 14
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469
Abacus Software
Atari ST Internals
Since the blitter is a DMA device, it must be able to transfer the processor in
an idle state. The processor needs the 68000 pins BR (Bus Request), BG
(Bus Grant) and BGACK (Bus Grant Acknowledge). The BG pin conveys
everything needed for the address and data bus. If the processor recognizes
a Bus Request, BG tells the attached device that there is now a bus available
for the DMA device. Now a short delay loop executes until the 68000 stops
its activity in the different pins (see Section 1.2). As long as the DMA entry
has established that the processor is no longer active, then it restarts with
the help of BGACK. After data transfer finishes, BGACK clears, and the
processor receives control of the bus.
The blitter chip can use the entire address range of the 68000 (16
megabytes). In order to manipulate the data in memory through
programming, the processor cannot produce any control signals. These
controlled by the READ/WRITE pin, which determines which data is read
and which is written to memory. Other important signals for accessing
memory are AS (Address Strobe), LDS (Lower Data Strobe) and UDS
(Upper Data Strobe).
The DTACK signal (Data Transfer Acknowledge) invokes the blitter chip
only, when the processor displays the transfer of data. It cannot do the
DMA transfer itself, since the RAM chip timing is set by the blitter or the
CLK signal. Like the other onboard DMA channels (floppy disk and DMA
port) and the ACIAs, the blitter is also capable of performing interrupts.
This means that it can create its own interrupts to end data transfers.
Therefore, it uses the free bit 3 of the MFP interrupt entry (GPIP). This
option is not usually used by the ST operatng system. However, other
interrupt-oriented operating systems like RTOS, OS9 or UNIX should have
blitter integration.
The last group of blitter connections belong to the power connections. In
addition to the usual 5 volt current and ground, the blitter needs a time
signal of 8 mHz.
470
Abacus Software
Atari ST Internals
4.3.1 The blitter registers
The ST blitter chip is the hardware implementation of the BITBLT algorithm
used in the line- A opcodes.
Figure 4.3. 1-1 shows a block diagram of the blitter functions. The blitter
can basically set up a source range which can be combined with a current
raster, a destination range of 16 different logical operands, and a destination
range in which it stores the result. Both source and destination ranges can
be stored in the same area of RAM. Unlike the processor, which can only
operate in bytes and words, the blitter is bit-oriented. This makes the blitter
ideal for handling bitmapped graphics. It is also practical for normal copy
and transfer commands, e.g., high-speed RAM disk operations without
hard disk interrupts.
The following is a look at the individual registers used by the blitter:
Figure 4.3.1-1 BLITTER BLOCK DIAGRAM
The first 16 registers are marked as half-tone RAM, and contain the raster
used in half-tone operations. The registers are each 16 bits wide. When the
raster is used, a proportional register for a lin is used. The raster repeats
over all 16 lines. The Line Number register (see below) determines which
half-tone register is used next.
471
Abacus Software
Atari ST Internals
Bit
F
E
D
c
B
A
9
8
7
6
5
4
3
2
1
0
$FF8A00
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
0
$FF8A02
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
1
$FF8A04
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
2
$FF8A06
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
3
$FF8A08
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
4
$FF8A0A
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
5
$FF8A0C
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
6
$FF8A0E
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
7
SFF8A10
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
8
$FF8A12
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
9
$FF8A14
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
10
$FF8A16
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
11
$FF8A18
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
12
$FF8A1A
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
13
$FF8A1C
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
14
$FF8A1E
R/W
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Half-tone
RAM
15
The next register is called X Increment. This is a leading character
dependent 15-bit register. The lowest bit is ignored and constantly registers
0. This makes only even numbers possible. The register gives the offset in
bytes in the next source word in the same line. Normally, the Atari gives a 2
for monochrome mode. This is also the case when all planes are copied in
color mode. If a plane is copied in medium-res or low-res mode, then 4 or 8
must exist in this register.
Bit FEDCBA987 6543210
$FF8A20 R/W XXXXXXXXXXXXXXXO Source X
| Increment
(always zero, even increments only)
The Source Y Increment register determines how many bytes must be added
to the current source address, in order to figure out the distance from the
end of the current line to the start of the next line.In monochrome mode, a
set of pixels measures 80 bytes: When only a segment of 20 bytes is copied,
the Source Y Increment gives a value of 60.
Bit FEDCBA987 6543210
$FF8A22 R/W XXXXXXXXXXXXXXXO Source Y
| Increment
(always zero, even increments only)
472
Abacus Software
Atari ST Internals
The Source Address register determines the starting address at the beginning
of the copy. It can read or write long word accesses. Bits 0 and 24-31 are
used only for even 24- bit addresses. The contents of this register are
incremented as part of the operation with the help of the above mentioned
increment register (or decremented, depending on the leading character of
the increment register). By reading the source address register, the address
of the source word used next is received.
Bit FEDCBA987 6543210
$FF8A2 4 R/w - -- -- -- - XXXXXXXO Source Address
High Word
(unused) (24-bit addresses only)
Bit FEDCBA987 6543210
$FF8A2 6 R/W XXXXXXXXXXXXXXXO Source Address
| Low word
(always zero, even increments only)
The next three registers contain the endmask, which states which bits are
changed and which are unchanged. Since the blitter is pixel oriented, but the
bus accesses RAM in words, the first and the last word are read as bits. To
write 16 bits over the processor bus, the destination word must first read
then change the allowable bits, and transfer the result (Read-Modify-Write).
Endmask 1 does this for the beginning of a line, endmask 3 applies to the
end of a line. Endmask 2 is used by all other words. It is normally set to
$FFFF (all bits are altered by it). Thus, a previous reading of the destination
word is unnecessary.
Bit FEDCBA9 87 6543210
$FF8A2 8 R/W XXXXXXXXXXXXXXXX Endmask 1
$FF8A2A R/W XXXXXXXXXXXXXXXX Endmask 2
$FF8A2C R/W XXXXXXXXXXXXXXXX Endmask 3
The next three registers are Destination X Increment, Destination Y
Increment and Destination Address. They have the same uses as the above-
mentioned source registers, except that these three apply to the destination.
Bit FEDCBA987 6543210
$FF8A2E R/W XXXXXXXXXXXXXXXO Destination X
| Increment
(always zero, even increments only)
473
Abacus Software
Atari ST Internals
Bit FEDCBA9876543210
$FF8A30 R/W XXXXXXXXXXXXXXXO Destination Y
I Increment
| (always zero, even increments only)
Bit FEDCBA987 6543210
$FF8A32 R/W ----- - -XXXXXXXX Destination
Address High Word
j (unused) (24-bit addresses only)
Bit FEDCBA987 6543210
$FF8A34 R/W XXXXXXXXXXXXXXXO Destination
I Address Low Word
I (always zero, even increments only)
The X Count register informs you how many words are in a destination
line. The minimum value is 1; the highest is 65536 ($0000). Reading the
register gives the number of values in this line as words are transferred.
When the X Count register is loaded with 1, the values in Destination X
! Increment, as well as Source X Increment, are unused. Since the line after a
word is already the end, and the corresponding Y Increment is used direct.
; The Y Count register determines the number of lines. The smallest value is
again one, and values of zero are interpreted as 65536. Reading this register
j gives you the number of lines which need copying. After every transferred
line, the value decrements by one until it reaches 0, ending the transfer.
Bit FEDCBA987 6543210
$FF8A36 R/W XXXXXXXXXXXXXXXX X-Count
j $FF8A38 R/W XXXXXXXXXXXXXXXX Y-Count
| All the abovemen tioned registers can only be read as words or long words;
byte access is not allowed.
The HOP register determines the combination of source and half-tone RAM.
j The two lowest bits have the following meanings:
(HOP Combination
0 All 1-bits
1 Half-tone RAM
; 2 Source
3 Source and half-tone RAM
474
Abacus Software
Atari ST Internals
You can therefore determine whether the source can be used unaltered (HOP
= 2), whether the half-tone RAM is combined with the logical AND (HOP =
3) or whether only the half-tone RAM is used (HOP =1). This is useful, for
example, when filling an area with a raster pattern. Furthermore, it is still
possible to fill the destination with 1-bits (HOP = 0). When half-tone RAM
is used, another register determines which half-tone registers are used.
Bit 76543210
$FF8A3A R/W - - - - XX HOP
Half-tone operation
The next register determines the receiver of the new destination value, after
logical operations between destination and source. Here are 16 different
options in the following table.
(~s&~d)
(~s&d) I (s&~d) | (s&d)
Operation New destination
0
0
0
0
all 0 bits
0
0
0
1
1
source AND destination
0
0
1
0
2
source AND NOT destination
0
0
1
1
3
source
0
1
0
0
4
NOT source AND destination
0
1
0
1
5
destination
0
1
1
0
6
source XOR destination
0
1
1
1
7
source OR destination
1
0
0
0
8
NOT source AND NOT destination
1
0
0
1
9
NOT source XOR destination
1
0
1
0
10
NOT destination
1
0
1
1
11
source OR NOT destination
1
1
0
0
12
NOT source
1
1
0
1
13
NOT source OR destination
1
1
1
0
14
NOT source OR NOT destination
1
1
1
1
15
all 1 bits
The most important operations are the following three (Replace mode,
Source replaces and destination), 6 (XOR mode; overlapping of destination
and source) and and 7 (OR mode).
Bit 76543210
$FF8A3B R/W - -XXXX OP
Logical operation
475
Abacus Software
Atari ST Internals
Line number
Unused
SMUDGE
HOG
Busy
The next register combines several functions. The lowest 4 bits determine
which of the 16 half-tone RAM registers are even used. The value is
incremented or decremented after a line, depending on the leading character
in the Destination Y Register. When the SMUDGE bit is set, the number of
the half-tone RAM register is determined by the four lowest bits of the
above mentioned source data. The selected half-tone operation (HOP) stays
active. This allows special effects.
The next bit in this register determines the method of bus access in the
blitter. When the HOG bit clears, the blitter and processor share the same
bus. After 64 bus cycles, the blitter stops and the processor takes over the
bus for 64 bus cycles. When the HOG bit is set, the processor stops until
the blitter finishes its operations. In either case, other DMA devices (floppy
and harddisk) have priority over the blitter. The Prefetch mechanism of the
68000 processor lets you bypass HOG mode, so after the start of the blitter
the next processor command executes when the blitter is ready.
The BUSY bit is set, initializing all other blitter registers, in order to start
the blitter. It waits until the blitter ends its operation. Since the interrupt
output mirrors the status of the blitter, blitter operations can be ended by an
interrupt taken from the third bit of the GPIP within the MFP 68901.
Bit 76543210
$FF8A3D R/W XX--XXXX
I
The last blitter register also has several functions. The lowest four bits
determine the source operand shifts, to protect the destination operations.
Since the blitter is bit-oriented, but bus access is word-oriented, the source
data must move to set the bit positions of half-tone masks and destination
data. Therefore, two source data words are read, shifting the relevant bits
for calling in a 16-bit source register (see Figure 4.3. 1-1).
SKEW
JJnused
_NFSR
FXSR
Bit 76543210
$FF8A3C R/W XXX-XXXX
I
476
Abacus Software
Atari ST Internals
FXSR and NFSR are abbreviations for Force eXtra Source Read and No
Final Source Read. When the FXSR bit is set, the beginning of each line is
read as an additional source word. The NFSR bit is set when the last word
of the source line cannot be read. The use of these bits require changes to
Source Y Increment and Source Address Register.
Normally you can access the blitter directly through the operating system.
When you use the line- A or VDI functions, the operating system can tell
whether the function is produced by software or by the blitter (see XBIOS
function $64).
477
Abacus Software
Atari ST Internals
4.4 The Mega ST realtime clock
When the ST was initially released, GEMDOS set the software-run clock in
two-second increments. In addition, the clock and date needed resetting
every time the user switched on the computer.
To get around this, the ROM circuits, keyboard processor and clock IC
offered some solutions. The Mega ST's clock IC is a permanent solution to
the problem. Its timekeeping registers are as follows:
Bit
7
6
5
4
3
2
1
0
(bits 4-7 unused)
$FFFC2 1
R/W
-
-
-
-
X
X
X
X
one second
$FFFC23
R/W
-
-
-
-
X
X
X
X
ten seconds
$FFFC25
R/W
-
-
-
-
X
X
X
X
one minute
$FFFC27
R/W
-
-
-
-
X
X
X
X
ten minutes
$FFFC2 9
R/W
-
-
-
-
X
X
X
X
one hour
$FFFC2B
R/W
-
-
-
-
X
X
X
X
ten hours
$FFFC2D
R/W
-
-
-
-
X
X
X
X
weekday
$FFFC2F
R/W
-
-
-
-
X
X
X
X
one day
$FFFC31
R/W
-
-
-
-
X
X
X
X
tenth day
$FFFC33
R/W
-
-
-
-
X
X
X
X
one month
$FFFC35
R/W
-
-
-
-
X
X
X
X
tenth month
$FFFC35
R/W
-
-
-
-
X
X
X
X
one year
$FFFC37
R/W
-
-
-
-
X
X
X
X
tenth year
$FFFC39
R/W
-
-
-
-
X
X
X
X
control register
$FFFC3B
R/W
-
-
-
-
X
X
X
X
control register
$FFFC3D
R/W
-
-
-
-
X
X
X
X
control register
The RP 5 C 15 appears to be the same as most clock ICs. It has a
four-bit- wide data and address bus, which addreses a total of 16 registers.
All of these registers had data width of 4 bits, and contain areas of date and
time in BCD format. The next three registers ($FFFC3B to $FFFC3F) are
unknown. They describe some registers of setting the clock, but
disassembly doesn't give any further information. Clock timing counts
through a quartz oscillator running at a frequency of 32,768 kHz. This
relatively slow IC is controlled through a PAL (programmable logic array).
All clock registers lie in the address area of the processor, offering a simple
to read and accurate clock. The Mega ST's operating system and XBIOS
functions determine theimselves whether the clock time is taken from the
keyboard processor, or whether the hardware clock is available at all.
478
Abacus Software
Atari ST Internals
4.5 Blitter chip demonstration programs
This section contains programs demonstrating some of the blitter chip’s
abilities.
This sample program moves the screen memory to another location. The
function blit is universal, however, you can blit any RAM. Try the program
as a test only. The main purpose of this program is to show how to
establish screen areas (forms) and pixel coordinates for the individual
registers of the blitter. This program directly accesses the blitter, and must
run in 68000 supervisor mode. If you attempt to run the program in user
mode, a bus error occurs.
blitter
equ
$ f f 8a00
t
blitter
register offsets
halftone
equ
0
src xinc
equ
$20
src_yinc
equ
$22
src_addr
equ
$24
ENDMASK1
EQU
$28
endmask2
equ
$2a
endmask3
equ
$2c
dst xinc
equ
$2e
dst yinc
equ
$30
dst addr
equ
$32
x count
equ
$36
y count
equ
$38
hop
equ
$3a
op
equ
$3b
line num
equ
$3c
skew
equ
$3d
t
blitter
register flags
f linebusy
equ
7 ;busy bit
r
mask blitter register bit
mhop src
equ
$02 /half-tone operation
mskewfxsr
equ
$80 ;fxsr mask
mskewnf sr
equ
$40 ;nfsr mask
479
Abacus Software
Atari ST Internals
mlinebusy
equ
$80 ;busy mask
physbase
equ
2 ;get screen address
xbios
equ
14
demo :
lea
para, a4
move
tphysbase, - (sp)
trap
#xbios
addq.l
#2, sp
;get screen address
move . 1
dO, src_form(a4)
; screen acts as
move . 1
d0,dst form(a4)
; source and destination
moveq
#2 , dO
;2 bytes offset
move
dO, src_nxwd (a4)
; to next word in
move
dO, dst_nxwd (a4 )
;same color plane
moveq
#80, dO
; one line is 80 bytes long
move
dO, src_nxln (a4 )
/ (monochrome mode)
move
dO, dst_nxln (a4)
moveq
#2 , dO
;offset to next color plane
move
dO, src_nxpl (a4)
;not used in
move
dO , dst_nxpl ( a4 )
/monochrome mode
move
#25, src_xmin (a4)
; xl-coordinate source
move
#34 , src_ymin (a4)
; y 1-coordinate source
move
#220,dst_xmin (a4)
; xl-coordinate destination
move
#234 , dst_ymin ( a.4 )
;yl-coordinate destination
move
#77, width (a4)
/width in pixels
move
#50, height (a4)
/height -pixels (number of lines)
move
#1 , planes (a4 )
/monochrome
jsr
blit_it
/access blitter
rts
/ ready
para
dc . w
17
/room for parameter block
/
end maskn
If endmask:
480
Abacus Software
Atari ST Internals
dc.w $ffff
rt endmask:
dc.w
$7f f f
dc.w
$3f f f
dc . w
$lfff
dc . w
$0fff
dc . w
$07 ff
dc . w
$03ff
dc . w
$01ff
dc.w
$00ff
dc.w
$007f
dc.w
$003f
dc.w
$001f
dc . w
$000f
dc.w
$0007
dc . w
$0003
dc.w
$0001
dc.w
$0000
input :
pointer to
34-byte parameter block in a4
src_form
equ
0
/base address source memory form
src nxwd
equ
4
/offset next word in source
src nxln
equ
6
/source form width
src nxpl
equ
8
/offset between source planes
src xmin
equ
10
/source xl
src ymin
equ
12
/source yl
dst form
equ
14
/base address dest memory form
dst nxwd
equ
18
/offset next word in dest
dst nxln
equ
20
/dest form width
dst_nxpl
equ
22
/offset between dst planes
dst xmin
equ
24
/dest xl
dst ymin
equ
26
/dest yl
width
equ
28
/width in pixels
height
equ
30
/height in pixels
planes
equ
32
/number of planes
blit it :
lea
blitter
, a5
481
Abacus Software
Atari ST Internals
compute xmax from xmm and width
move width (a4),d6
subq #l,d6
move src_xmin (a4 ) , dO
move dO,dl
add d6,dl
move dst_xmin (a4 ) , d2
move d2,d3
add d6,d3
moveq #$f,d6
move d2,d4
and d6,d4
add d4 , d4
move lf_endmask(pc,d4) ,d4
move d3,d5
and d6,d5
add d5 , d5
move rt_endmask (pc, d5) , d5
not d5
calculate skew
( (dst_xmin mod 16) - <src_xmin
determine FXSR and NFSR
/width -1
;src xmax
;dst_xmax
/mod 16 mask
zdst_xmin
/dst_xmin mod 16
/pointer to left end mask table
/left end mask
/dst_xmax
zdst_xmax mod 16
/pointer to right end mask
/table
/inverted left end mask
/right end mask
mod 16)) mod 1 6
3 bit index in table
bit 0 0 src_xmin mod 16 >= dst_xmin mod 16
1 src_xmin mod 16 > dst_xmin mod 16
bit 1 0 src_xmax/16 - src_xmin/16 <> dst_xmax/16 -
dst_xmin/16
0 src xmax/16 - src_xmin/16 <> dst_xmax/16 -
dst_xmin/16
bit 2 0 dst_span equals several words
1 dst_span equals one word
move d2,d7 /dst_xmin
482
Abacus Software
Atari ST Internals
and d6,d7 ;dst_xmin mod 16
and d0,d6 ;src_xmin mod 16
sub d6,d7 ;dst_xmin mod 16 - src_xmin mod 16
> ? cy = 1 : cy = 0
clr d6 /delete index in table
addx d6,d6 ;cy after bit 0
lsr #4,d0 ;src_xmin / 16
lsr #4 , dl ;src_xmax / 16
sub dO , dl ;src_span - 1
lsr #4,d2 ;dst_xmin / 16
lsr #4,d3 ;dst_xmax / 16
sub d2,d3 ;dst_span - 1
bne set_endmask
if
if dst span = one word, both endmasks stand in endmask 1
the blitter ignores endmask 2
and
d5,d4
addq
#4,d6 ;d6 bit 2
= 1 one word destination
set_endmask :
move
d4 , endmaskl (a5)
/left endmask
move
#$f ff f , endmask2 ( aS )
/middle endmask
move
d5, endmask3 (a5)
/right endmask
cmp
dl, d3
/number of source und dest words
/ equal?
bne
set count
/ no
addq
#2,d6
/ d6 bit 1=1 equal number of
/ words
set_count :
move
d3,d4
addq
#1, d4
/number of words in dest line
move
d4,x count (a5)
}
; determine
source start address
src form + (src_ymin * src_nxln) * (src_xmin/16 * src_nxwd)
483
Abacus Software
Atari ST Internals
move . 1
src form (a4 ) , aO
;a0 -> start src form
move
src ymin (a4 ) , d4
; offset in lines to ymin
move
src_nxln (a4 ) , d5
;length src line
mulu
d5,d4
add. 1
d4 , aO
;a0 -> (0, ymin)
move
src nxwd(a4) ,d4
; offset of next word
move
d4 , src_xinc (a5)
mulu
d4,d0
add.l
dO, aO
;a0 -> first word (xmin, ymin)
mulu
d4,dl
;source line length in bytes
sub
dl, d5
move
d5, src_yinc (a5)
/offset next end line beginning
compute
destination start address
move . 1
dst_form(a4) , al
;al -> start dst form
move
dst_ymin ( a4 ) , d4
move
dst_nxln (a4 ) , d5
mulu
d5,d4
add.l
d4 , al
move
dst_nxwd(a4) ,d4
move
d4 , dst_xinc (a5)
mulu
d4,d2
add . 1
d2, dl
compute
dst yinc
mulu
d4,d3
sub
d3,d5
move
d5,dst yinc(a5)
/destination y increment
and . b
#$f , d7
or . b
skew_f lags (pc, d6)
,d7 /skew-flags from table
move . b
d7 , skew (a5)
;in blitter
move . b
#mhop_src, hop (a5)
/half-tone operation: source only
move . b
#3, op (a5)
/replace mode
lea
line num (a5) , a2
/pointer to line number register
484
Abacus Software
Atari ST Internals
move . b
#f linebusy, d2
;busy bit after d2
move
planes ( a4 ) , d7
/number of bitplanes
bra
begin
skew flags:
dc . b
mskewnf sr
dc.b
mskewfxsr
dc.b
0
dc . b
mskewnf sr+mskewf xsr
dc.b
0
dc.b
mskewfxsr
dc.b
0
dc.b
0
next plane:
move . 1
aO, src_addr (a5)
;load source address
move . 1
al, dst_addr (a5)
;load destination addre:
move
height (a4 ), y_count (a5) ; number of lines
move .b
#mlinebusy, (a2)
,-start blitter
add
src_nxpl (a4) , aO
/start next src plane
add
dst_nxpl (a4 ) , al
/start next dst plane
restart :
bset
d2 , (a2 )
/restart blitter
nop
bne
restart
;not ready yet?
begin
dbra
d7 , next_plane
/next bitplane
rts
end
Here are some extremely interesting sample programs for the BITBLT
line- A command.
The first example defines a monochrome picture and copies it to a
monchrome screen. The picture should appear on the screen starting at the
coordinates X = 200 and Y = 100. This replaces the original screen contents
using the replace mode. No raster is used, so the raster address is set to
zero. The program looks like this:
485
Abacus Software
Atari ST Internals
***********************************************************************
bitblt demo *
copy one-color source range to monochrome screen *
★★★★**•***★★★**★******★★★**★★*★★*★*★*★**★★★*****★***★***★**★*★**★****★*★
bitblt
equ
$a007
/op code
b width
equ
0
/width in pixel
b height
equ
2
/height in pixel
planes
equ
4
/number of colorplanes
fg col
equ
6
/foreground color
bg col
equ
8
/background color
op tab
equ
10
/logical operations
s_xmin
equ
14
/ x-coordinate in source
s ymin
equ
16
/y-coordinate in source
s_form
equ
18
/address of source
s nxwd
equ
22
/offset of next word in source
s_nxln
equ
24
/offset of next line in source
s_nxpl
equ
26
/offset of next colorplane in source
d_xmin
equ
28
/x-coordinate in destination
d_ymin
equ
30
/y-coordinate in destination
d form
equ
32
/address of destination
d_nxwd
equ
36
/offset of next word in destination
d_nxln
equ
38
/offset of next line in destination
d_nxpl
equ
40
/offset of next colorplane in
/destination
p addr
equ
42
/address of raster used
p nxln
equ
46
/offset of next line in raster
p_nxpl
equ
48
/offset of next colorplane in raster
p_mask
equ
50
/raster index mask (number of lines)
physbase
equ
2
xbios
equ
14
do blit
lea
para(pc),a6 /pointer to parameter block
move
#92, b_
width (a6) /width in pixel
move
#52, b_
height (a6) /height in pixel
move
#1, planes (a6) /monochrome
move
#i» fg.
col(a6) /foreground color
move
#0, bg_
col(a6) /background color
486
Abacus Software
Atari ST Internals
para :
source
move . 1
#$03030303, op_tab (a6) /replace mode
move
move
move . 1
#0, s_xmin (a6)
#0, s_ymin (a6)
♦source, s_form (a6)
transfer source data
/upper left corner of source
/source address
move
move
move
#2,22 (a6)
#12 , s_nxln (a6)
#2, s_nxpl (a6)
/ 2 byte offset of next word
/ 80 byte offset of next
/ line
/2 byte offset of next
/ colorplane
screen is destination
move
move
#2 00, d_xmin ( a 6 )
#100, d_ymin ( a 6 )
/ x-coordinate of screen
/ y-coordinate of screen
move
trap
addq . 1
♦physbase, - (sp)
#xbios
#2, sp
/get screen address
move . 1
dO, d_form (a6)
/as destination address
move
move
move
#2,d_nxwd(a6)
#80,d_nxln <a6)
#2 , d_nxpl (a6)
/ 2 byte offset of next word
/ 80 byte offset of next line
/ 2 byte offset of next
/ colorplane
clr . 1
p addr(a6)
/no raster used
dc.w
rts
bitblt
/execute bitblt
align
ds . b
76 ; 76 byte
parameter block
width = 92 width of source in pixels
height = 52 height of source in pixels
dc.w $AAAA, $AAAA, $AAAA, $AAAA, $AAAA, $AAA0
dc.w $5555, $5555, $5555, $5555, $5555, $5550
dc . w $AAAA, $AAAA, $AAAA, $AAAA, $AAAA, $AAA0
dc.w $5555, $5555, $5555, $5555, $5555, $5550
dc.w $AAAA, $AAAA, $AAAA, $AAAA, $AAAA, $AAA0
dc.w $5555, $5555, $5555, $5FD5, $5555, $5550
487
Abacus
end
Software
Atari ST Internals
dc.w
$AAAA, $AAAA,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAA,
dc.w
$D555, $5555,
dc.w
$EAAA, $AAAA,
dc.w
$F555, $5555,
dc.w
$FAAA, $AAAA,
dc.w
$FD55, $5555,
dc.w
$E0AA, $AAAA,
dc.w
$6555, $5555,
dc.w
$B2AA, $AAAB,
dc.w
$3555, $5555,
dc.w
$9 AAA, $AAAB,
dc.w
$5955, $5555,
dc . w
$A2 AA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAB,
dc.w
$5540, $0000,
dc . w
$AAA0, $0000,
dc.w
$5543, $C71E,
dc.w
$AAA2, $2220,
dc.w
$5542, $221C,
dc.w
$AAA2, $2202,
dc.w
$5543, $C73C,
dc.w
$AAA0, $0000,
dc.w
$5540, $0000,
dc.w
$AAA0, $0000,
dc.w
$5555, $5555,
dc . w
$AAAA, $AAAA,
dc . w
$5555, $5555,
dc . w
$AAAA, $AAAA,
dc.w
$5555, $5555,
dc.w
$AAAA, $AAAA,
dc . w
$5555, $5555,
$AAAA, $B06A, $AAAA, $AAA0
$55FF, $E03D, $5555, $5550
$AB83, $000A, $AAAA, $AAA0
$57 01, $FFEF, $5555, $5550
$ACOO, $002A, $AAAA, $AAA0
$5FF7, $F7A7, $5555, $5550
$B00C, $18AE, $AAAA, $AAA0
$7FF8, $0E9B, $5555, $5550
$C000, $02B2 , $AAAA, $AAA0
$FFFF, $FC63, $5555, $5550
$0000, $04C6, $AAAA, $AAA0
$0700, $058B, $5555, $5550
$0880, $0712, $AAAA, $AAA0
$0F80, $0627, $5555, $5550
$0880, $04 4A, $AAAA, $AAA0
$0880, $0493, $5555, $5550
$0000, $0522, $AAAA, $AAA0
$03FC, $0647, $5555, $5550
$0204, $048C, $AAAA, $AAA0
$02 04, $0519, $5555, $5550
$03FC, $0632, $AAAA, $AAA0
$0000, $0465, $5555, $5550
$0000, $04CA, $AAAA, $AAA0
$060C, $0595, $5555, $5550
$0FF8, $072A, $AAAA, $AAA0
$0000, $0655, $5555, $5550
$0000, $04AA, $AAAA, $AAA0
$0000, $0555, $5555, $5550
$FFFF, $FEAA, $AAAA, $AAA0
$0000, $0000, $0000, $1550
$0000, $0000, $0000, $0AA0
$4 9EF, $ 9CF9, $C722, $1550
$5202, $2220, $88B2, $0AA0
$61C2 , $3E20, $88AA, $1550
$5022, $2220, $88A6, $0AA0
$4BC2, $2221, $C722, $1550
$0000, $0000, $0000, $0AA0
$0000, $0000, $0000, $1550
$0000, $0000, $0000, $0AA0
$5555, $5555, $5555, $5550
$AAAA, $AAAA, $AAAA, $AAA0
$5555, $5555, $5555, $5550
$AAAA, $AAAA, $AAAA, $AAA0
$5555, $5555, $5555, $5550
$AAAA, $AAAA, $AAAA, $AAA0
$5555, $5555, $5555, $5550
488
Abacus Software
Atari ST Internals
The next example tests out raster use. A raster is basically a graphic area
which combines with a source range through a logical AND, and the desired
logical operation is copied to the destination range. The comparison of the
source range with the raster naturally occurs within the BITBLT function.
The source range itself stays independent.
p mask and p addr correspond to the variables _patptr and _patmsk
through the function $A004, HORIZONTAL LINE. The variable p nxln
gives the offset for the next line of the raster, and must be an even number,
so a line from any number of 16 bit words must coincide, as well as source
and destination.
A raster can usually be multicolor. The individual bitplanes must then be
overlapped word for word as described in the beginning of this chapter. The
raster index mask (p_mask) gives which raster line should be combined
with the source line. From the source line the number of raster line comes
from AND and p mask. This is the usual count:
Raster Lines p_mask
2 1
4 3
8 7
16 15
The blitter has 16 registers of 16 bits into which a raster can be loaded.
This sample program is almost identical to the earlier BITBLT demo. Just
replace the material at the do_blit and raster labels with the coding
below. Then save the new version of BITBLT under another name.
bitblt demo changes
copy one-color range to monchrome screen using a raster
*
★
*
★
★
do blit
lea
para (pc) , a6
;pointer to parameter block
move
#92,b_width (a6)
; width in pixels
move
#52 , b_height <a6)
/height in pixels
move
#1 , planes (a6)
; monochrome
489
Abacus Software
Atari ST Internals
move
move
#1, fg_col (a6)
#0, bg_col (a6)
/foreground color
/background color
move • 1
#$03030303, op_tab (a6) /replace mode
move
move
move . 1
#0, s xmin (a6)
#0, s ymin (a6)
♦ source, s_form (a6)
transfer source data
/source from upper left corner
/source address
move
move
move
#2, s nxwd(a6)
#12, s_nxln ( a 6 )
#2,s nxpl(a6)
/ 2 byte offset to next word
/80 byte offset to next line
/2 byte offset - next color plane
dest is screen
move
move
#200, d_xmin (a6)
#100, d_ymin (a6)
/ x-coordinate on screen
/ y-coordinate on screen
move
trap
addq . 1
♦physbase, - (sp)
#xbios
#2 , sp
/get screen address
move . 1
d0,d_form(a6)
/use as dest address
move
move
move
#2,d nxwd(a6)
#80,d_nxln (a6)
#2,d_nxpl (a6)
/2 byte offset of next word
/80 byte offset to next line
/ 2 byte offset of next color
/plane
move . 1
move
move
move
♦raster, p_addr (a6)
#2, p_nxln (a6)
#0, p_nxpl (a6)
#1, p_mask ( a 6 )
/use raster
/offset of next raster
/single color raster
/raster index mask
dc . w
rts
bitblt
/execute bitblt
align
raster
dc.w
dc.w
%1010101010101010
%0101010101010101
/first raster line
/second raster line
para :
ds . b
76 /76-byte
parameter block
; source and rest of original program follow....
Every other pixel is deleted, giving us a raster.
490
Abacus Software
Atari ST Internals
Index
address bus
asynchronous bus control
ADDRESS STROBE (AS)
DTACK
LOWER DATA STROBE (LDS)
READ/WRITE (RAV)
UPPER DATA STROBE (UDS)
Asynchronous Communications Interface Adapter (ACIA)
pins
registers
7,8
8-9
8
9-12
8
8
8
41-47,62-63
41-44
45-47
BANK
Basic Input Output System (BIOS)
listing
BCD — see Binary Coded Decimal
BERR
BG — see Bus Grant
BGACK — see Bus Grant Acknowledge
BGO — see Bus Grant Out
Binary Coded Decimal (BCD)
BIOS— see Basic Input Output System
BLANK
Blitter chip
Bus Grant (BG)
Bus Grant Acknowledge (BGACK)
Bus Grant Out (BGO)
Bus Request (BR)
cartridge slot
Centronics interface
CLK
data bus
data registers
Data Request (DR)
DE — see Display Enable
Digital Research
Direct Memory Access (DMA)
Display Enable (DE)
55
152-163,245,250
271-461
11-15
4
15
204-205,469-476,484-496
10,13
10,13
13
1013
96-98
88-89
11
7
4
22
105
8-9,12-13,18-19,25,58-59,101-102
DMA — see Direct Memory Access
DR — see Data Request
491
Abacus Software
Atari ST Internals
exception vectors
235-237
FDC — see Floppy Disk Controller
Floppy Disk Controller (FDC)
20-27
Command Register (CR)
24
Data Register (DR)
24
Sector Register (SR)
24
Status Register (STR)
24
Track Register (TR)
24
floppy disk interface
99-100
GEM graphics
206-234
high-res
207-210
line-A opcodes
227-234
line-A variables
224-226
lo-res
206-209
medium-res
205-207
GEM graphic commands
211-224
BITBLT
215-217
COPY RASTER FORM
224-225
CONTOUR FILL
223-224
DRAW SPRITE
222-223
FILLED POLYGON
214-215
FILLED RECTANGLE
213-214
GET PIXEL
211
HIDE CURSOR
221
HORIZONTAL LINE
213
Initialize
211
LINE
212
PUT PIXEL
211
SHOW MOUSE
220
TEXTBLT
217-222,232-235
TRANSFORM MOUSE
221,230-231
UNDRAW SPRITE
221-222,221-222
GEMDOS
105-151,245
functions
106-151
error messages
151
GLUE
13-15, 18,69
HALT
11,12
HSYNC
15
492
Abacus Software
Atari ST Internals
IACK 13
integrated circuits
INTEL
interrupts
I/O registers
ACIAs
DMA/Disk Controller
keyboard
MFP 68901
MIDI
sound chip
Video Display Register
3-63
3
7,10,240-244
55- 63
62
58- 59
62
60-61
62
59- 60
56- 58
keyboard control
67-71,74-84
line-F emulator
longword
238-239
7
Memory Management Unit(MMU)
memory maps
MFP 68901 — see Multi-Function Peripheral
MFPINT
MIDI — see Musicial Instrument Digital Interface
MMU — see Memory Management Unit
Motorola 68000 microprocessor
instruction set
mouse
MS-DOS
11,13,15-16,18,55
62-63
13
3-12,258-270
258-270
71-74
106, 186
Multi-Function Peripheral(MFP 68901)
Active Edge Register(AER)
connections
Data Direction Register(DDR)
General Purpose I/O Interrupt Port(GPIP)
Interrupt Enable Register(IERA,IERB)
Interrupt In-Service Register(ISRA,ISRB)
Interrupt Mask Register(IMRA,IMRB)
Interrupt Pending Register(IPRA,IPRB)
Receiver Status Regis ter(RSR)
registers
Synchronous Character Register(SCR)
Timer A/B Control Register(TACR,TBCR)
Timers C and D Control Register(TCDCR)
28-40,60-61,90,171,242-244
32
28-32
32
32
33
34
34
33-34
38-39
32-40
37
35
36
493
Abacus Software
Atari ST Internals
Timer Data Registers (T ADR,TBDR,TCDR,TDDR) 37
Transmitter Status Register(TSR)
39-40
UCR/USART
37-38
UDR/USART
40
Vector Register(VR)
34
Musical Instrument Digital Interface(MIDI)
NMI — see Non-Maskable Interrupt
93-95,177
Non-Maskable Interrupt (NMI)
6,13,240
operating system
105
PSG (Programmable Sound Generator) — see YM-2149 Sound Generator
RESET
11-12
RS-232 interface
90-92,243-244
SHIFTER
13,15,17,18
status register
6
supervisor mode
4,6,7,235
synchronous bus control
9
E
9
Valid Memory Address (VMA)
9
Valid Peripheral Address (VPA)
9,10
system fonts
465-466
system variables
250-257
Tramiel Operating System (TOS)
105
UNIX
106
user mode
4,6,7,235
video interface
85-87
VSYNC
15
VT52 emulator
245-249
WD 1772
20-27
word
7
word access
8
XBIOS
164-205
YM-2149 Sound Generator
48-54
494
Optional Diskette
For your convenience, the program listings contained in this book are
available on an SF354 formatted floppy disk. You should order the diskette
if you want to use the programs, but don’t want to type them in from the
listings in the book.
All programs on the diskette have been fully tested. You can change the
programs for your particular needs. The diskette is available for $14.95 plus
$2.00 ($5.00 foreign) for postage and handling.
When ordering, please give your name and shipping address. Enclose a
check, money order or credit card information. Mail your order to:
Abacus Software
P.O.Box 318
Grand Rapids, MI 49588
Or for fast service, call 616-698-0330.
Selected Abacus Products for the
AssemPro
Machine language development system
for the Atari ST
".../ wish I had (AssemPro) a year and a half ago... it
could have saved me hows and hows and hows."
— Kurt Madden
ST World
"The whole system is well designed and makes the rapid
development of 68000 assembler programs very easy."
— Jeff Lewis
Input
AssemPro is a complete machine language development
package for the Atari ST. It offers the user a single,
comprehensive package for writing high speed ST
programs in machine language, all at a very reasonable
price.
AssemPro is completely GEM-based — this makes it
easy to use. The powerful integrated editor is a breeze to
use and even has helpful search, replace, block,
upper/lower case conversion functions and user definable
function keys. AssemPro's extensive help menus
summarizes hundreds of pages of reference material.
The fast macro assembler assembles object code to
either disk or memory. If it finds an error, it lets you
correct it (if possible) and continue. This feature alone
can save the programmer countless hours of debugging.
The debugger is a pleasure to work with. It features
single-step, breakpoint, disassembly, reassembly and
68020 emulation. It lets users thoroughly and
conveniently test their programs immediately after
assembly.
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AssemPro Features:
• Full screen editor with dozens of powerful features
• Fast 68000 macro assembler assembles to disk or
memory
• Powerful debugger with single-step, breakpoint,
68020 emulator, more
• Helpful tools such as disassembler and reassembler
• Includes comprehensive 175-page manual
AssemPro Suggested retail price: $59.95
Atari ST, 52GST, 1040 ST, TOS, ST BASIC and ST LOGO are trademarks or registered trademarks of Atari Corp. —
GEM is a registered trademark of Digital Research Inc.
BeckerText ST
The High-Powered Word
Processing Package for the ST
A word processing package for serious Atari ST owners.
Because BeckerText is more than a word processor.
It has all the features of our TextPro, and more:
WYSIWYG formatting and printing, graphic merge
capabilities, automatic hyphenation and indexing of your
documents.
But BeckerText also does a few things that you might
not expect... like calculate numbers within. text, with
templates for calculations in up to five columns. (It's just
like having a spreadsheet program built into your word
processor!). BeckerText prints up to five columns of
text a page for professional-looking newsletters,
presentations, reports, etc. It even has two expandable
spelling checkers for 100% spelling accuracy.
BeckerText is also. a perfect choice for C language
programmers as an extremely flexible C editor. Whether
you’re deleting, adding or duplicating a block of C source
code, BeckerText does it all, automatically. The online
dictionary can double as a C syntax checker — catch those
syntax errors immediately.
BeckerText gives you the power and flexibility to
produce the professional-quality documents that you
demand. It adapts to, most popular dot-matrix and letter-
quality printers. Includes a comprehensive tutorial, manual
and glossary.
When you need more from your word processor than just
word processing, you need BeckerText. Discover the
power of BeckerText.
Suggested retail price: $99.95
BeckerText
BeckerText Features:
• Select options from dropdown menus or shortcut keys
• Fast WYSIWYG formatting
• Bold, italic, underline, superscript and subscript
characters
• Automatic wordwrap and page numbering
• Sophisticated tab and indent options, with centering &
margin justification
• Move, Copy, Delete, Search & Replace options
• Automatic hyphenation & automatic indexing
• Write up to 999 characters per line with horizontal
scrolling feature
• Online dictionary checks spelling as you're writing
• Spelling checker interactively proofs text
• Calculates numbers within text — use templates to
calculate in columns
• Customize up to 30 function keys to store often-used
text and macro commands
• Merge graphics into documents
• Includes BTSnap program for converting text blocks
to graphics
• C-source mode for quick and easy C language program
editing
• Multiple-column printing — up to five columns on a
single page
• Adapts to virtually any dot-matrix or letter-quality
printer
• Load & save files through the RS-232 port
• Comprehensive tutorial and manual
• Not copy protected
Aurt ST, 520ST, 1WOST, TOS, ST BASIC ST LOGO u* mtomita (. tntemrk, of Auri Cap.
OEM ia ■ registered trademark of Digital Research Inc.
Selected Abacus Products for the
rM
Chartpak ST
Professional-quality charts and graphs
on the Atari ST
In the past few years, Roy Wainwright has earned a
deserved reputation as a topnotch software author.
Chartpak ST may well be his best work yet. Chartpak
ST combines the features of his Chartpak programs for
Commodore computers with the efficiency and power of
GEM on the Atari ST.
Chartpak ST is a versatile package for the ST that lets
the user make professional quality charts and graphs
fast.. Since it takes advantage of the STs GEM
functions, Chartpak ST combines speed and ease of use
that was unimaginable til now.
The user first inputs, saves and recalls his data using
Chartpak ST's menus, then defines the data positioning,
scaling and labels. Chartpak ST also has routines for
standard deviation, least squares and averaging if they are
needed. Then, with a single command, your chart is
drawn instantly in any of 8 different formats — and the
user can change the format or resize it immediately to
draw a different type of chart.
In addition to direct data input, Chartpak ST interfaces
with ST spreadsheet programs spreadsheet programs
(such as PowerLedger ST). Artwork can be imported
from PaintPro ST or DEGAS. Hardcopy of the finshed
graphic can be sent most dot-matrix printers. The results
on both screen and paper are documents of truly
professional quality.
Your customers will be amazed by the versatile,
powerful graphing and charting capabilities of Chartpak
ST .
Chartpak ST works with Atari ST systems with one or
more single- or double-sided disk drives. Works with
either monochrome or color ST monitors. Works with
most popular dot-matrix printers (optional).
Chartpak ST Suggested Retail Price: $49.95
L
Selected Abacus Products for the ^ *e4ki^U™
DataRetrieve
(formerly FilePro ST)
Database management package
for the Atari ST
"DataRetrieve is the most versatile, and yet simple,
data base manager available for the Atari 520ST/1040ST
on the market to date."
— Bruce Mittleman
Atari Journal
DataRetrieve is one of Abacus' best-selling software
packages for the Atari ST computers — it's received
highest ratings from many leading computer magazines.
DataRetrieve is perfect for your customers who need a
powerful, yet easy to use database system at a moderate
price of $49.95.
DataRetrieve's drop-down menus let the user quickly and
easily define a file and enter information through screen DataRetrieve Features:
templates. But even though it's easy to use,
DataRetrieve is also powerful. DataRetrieve has fast . Easily define your fi]es usjng drop-down menus
search and sorting capabilities, a capacity of up to . Design screen mask size to 5000 by 5000 pixels
j 64,000 records, and allows numeric values with up to . choose from six font sizes and six text styles
15 significant digits. DataRetrieve lets the user access . Add circles, boxes and lines to screen masks
data from up to four files simultaneously, indexes up to . EaS( search and sort capabilities
20 different fields per file, supports multiple files, and . Handles records up to 64,000 characters in length
j has an integral editor for complete reporting capabilities. . Organize files with up to 20 indexes
• Access up to four files simultaneously
DataRetrieve's screen templates are paintable for . Cut, past and copy data to other files
enhanced appearance on the screen and when printed, and . change file definitions and format
data items may be displayed in multiple type styles and . Create subsets of files
font sizes. . interfaces with TextPro files
• Complete built-in reporting capabilities
The package includes six predefined databases for . change setup to support virtually any printer
mailing list, record/video albums, stamp and coin . Add header, footer and page number to reports
collection, recipes, home inventory and auto . Define printer masks for all reporting needs
maintenance that users can customize to their own . g^d output to screen, printer, disk or modem
requirements. The templates may be printed on Rolodex . includes and supports RAM disk for high-speed
cards, as well as 3 x 5 and 4 t 5 index cards. 1040ST operation
DataRetrieve's built-in RAM disks support lightning- . Capacities: max. 2 billion characters per file
fast operation on the 1040ST. DataRetrieve interfaces to niax. 64,000 records per file
TextPro files, features easy printer control, many help max. 54,000 characters per record
screens, and a complete manual. max. fields: limited only by record size
DataRetrieve works with Atari ST systems with one or
more single- or double-sided disk drives. Works with
either monochrome or color monitors. Printer optional.
DataRetrieve Suggested Retail Price: $49.95
max. 32,000 text characters per field
max. 20 index fields per file
• Index precision: 3 to 20 characters
• Numeric precision: to 15 digits
• Numeric range ±10"^ ti ±10^8
Atari ST, 520ST, 1040ST, TOS, ST BASIC and ST LOOO art trademarks or registered trademarks of Atari Carp.
GEM is a registered trademark of Digital Research Inc.
Selected Abacus Products for the
PaintPro
Design and graphics software for the ST
PaintPro is a very friendly and very powerful package
for drawing and design on the Atari ST computers that
has many features other ST graphic programs don't
have. Based on GEM™, PaintPro supports up to three
active windows in all three resolutions — up to 640x400
or 640x800 (full page) on monochrome monitor, and
320 x 200 or 320 x 400 on a color monitor.
PaintPro's complete toolkit of functions includes text,
fonts, brushes, spraypaint, pattern fills, boxes, circles
and ellipses, copy, paste and zoom and others. Text can
be typed in one of four directions — even upside down —
and in one of six GEM fonts and eight sizes. PaintPro
can even load pictures from "foreign" formats (ST
LOGO, DEGAS, Neochrome and Doodle) for
enhancement using PaintPro's double-sized picture
format. Hardcopy can be sent to most popular dot¬
matrix printers.
PaintPro Features :
• Works in all 3 resolutions (mono, low and medium)
• Four character modes (replace, transparent, inverse
XOR)
• Four line thicknesses and user-definable line pattern
• Uses all standard ST fill patterns and user definable
fill patterns
• Max. three windows (dependng on available memory)
• Resolution to 640 x400 or 640x800 pixels
(mono version only)
• Up to six GDOS type fonts, in 8-, 9-, 10-, 14-, 16-,
18-, 24- and 36-point sizes
• Text can be printed in four directions
• Handles other GDOS compatible fonts, such as those
in PaintPro Library # 1
• Blocks can be cut and pasted; mirrored horizontally
and vertically; marked, saved in LOGO format, and
recalled in LOGO
• Accepts ST LOGO, DEGAS, Doodle & Neochrome
graphics
• Features help menus, full-screen display, and UNDO
using the right mouse button
• Most dot-matrix printers can be easily adapted
PaintPro works with Atari ST systems with one or
more single- or double-sided disk drives. Works with
either monochrome or color ST monitors. Printer
optional.
PaintPro Suggested Retail Price: $49.95
PaintPro
Create double¬
sized pictures
PaintPro
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Atari ST, 520ST, 1 (MOST, TOS, ST BASIC and ST LOGO are trademarks or registered trademarks of Atari Corp.
GEM is a registered trademark of Digital Research Inc.
Selected Abacus Products for the
PCBoard
Designer
Interactive CAD Package
for printed circuit board layout
on the Atari ST
PCBoard Designer is an interactive, computer-aided
design package for creating electronic printed circuit
boards. It drastically reduces the cost, time and tedium of
making one or two-sided pc boards. The advanced
features of PCBoard Designer can improve a designer s
productivity ten-fold.
PCBoard Designer is easy to use. Design parameters are
conveniendy entered and modified at the computer. The
user can position the components interactively by
moving them on the screen using the mouse. This lets
the user compare alternative component placement with
no extra effort.
As the user position the components on the screen
using the mouse, PCBoard Designer displays the new
connections! Automatic routing is fast and precise.
The most powerful feature of PCBoard Designer is its
fast automatic routing capability. Traces are
automatically and precisely drawn on the screen. If the
user changes the design, the traces can be immediately
redrawn — this feature alone can save an enormous
amount of time and money. In addition, the user has
options of 4S° or 90“ angle traces, different trace widths,
routing from pin to pin, pin to BUS, BUS to BUS, as
well as two-sided boards. The rubberbanding feature lets
you see the user-defined components during
placement — and the user can reposition your
components at any time during the design process.
PCBoard Designer prints the completed layout to any
Epson/compatible dot matrix printer and Hewlett-
Packard plotters at 2:1. The high-quality printout is
camera-ready for final photo-etching. PCBoard Designer
also prints the component layout, and lists every
component and connection as well.
In conjuction with the Atari ST computer, PCBoard
Designer is the most affordable PC board CAD package
available. It boasts features that not available on
systems costing thousands of dollars.
PCBoard
Designer
Create printed circuit board layouts
Features: Auto-routing, component
list, pinout list, net list
How PCBoard Designer works
There are basically four steps in creating a working
pc board:
• Specify the components: For example, IC4 is an
integrated circuit that fits in a 14-pin dual-in-line
socket. You can also define custom component
types, for example a 99-pin circular IC.
• Specify the connections: For example, pin 2 of
integrated circuit IC4 is connected to lead 1 of
transistor Q7. You can change the connections at
any time.
• Position the components: Move the components
to their desired position on the screen by using
the Atari STs mouse. You can reposition them at
any time. PCBoard Designer automatically routes
the connections when you're done.
• Output the design: The finished board can be
printed on any Epson/compatible printer or
Hewlett-Packard plotter. The printout is suitable
for photoetching. You can also print the
component layout (for silkscreening), the
component list, and the list of connections. _
Atari ST, 520ST, 1040ST, TOS, ST BASIC arel ST LOGO are trademarks or registered trademarks of Atari Corp.
GEM is a registered trademark of Digital Research Inc.
Selected Abacus Products for the
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"I was thoroughly impressed... a powerful, multi-
featured design tool that can be easily learned and
used."
— Bill Marquardt
Input magazine
"What makes this program especially easy to use
is that the components are drawn to scale on the
screen. This comes in handy when it's time for
the user to position the components.
"The author invested a lot of blood, sweat and
tears writing this portion of the program. PCBoard
Designer has a wide selection of options here that
allow for flexible design. Either all of the
connections or an individual connection can be
routed at the click of the mouse button.
"One thing is clear, though: author Florian
Sachse has produced afirst-class software package.
This program will undoubtedly be a godsend to the
engineer and electronic hobbyist alike.
— DATA WELT Magazine
APRIL 1986
PCBoard Designer (continued)
If
PCBoard Designer Features:
| • PC boards may be one-sided or two-sided
| • Components are drawn to scale on the screen
| • Custom components may be used
| • Component positioning is flexible and interactive
| • Components may be roatated in 90s increments
!| • Traces are drawn using sophisticated and fast
automatic routing techniques — the user has the ability
to make 45° and 90° angle traces, variable trace
widths, pin to pin, pin to bus and bus to bus routing
| • "Blockades" may be inserted onto the board to handle
; special cases
| • Printout is high quality and suitable for photo-
| reproduction
j • Features are clearly displayed and are selectable from
the drop-down menus
j- , Hardware Requirements:
Computer: Atari 520ST or 1040ST computer and
| monochrome monitor with one or more single-sided,
1 double-sided, or hard disk drives.
I Printers/Plotters: PCBoard Designer prints your
| completed layout to any Epson or Epson-compatible dot
I matrix printer at 2:1. Epson FX-80, FX-100, Toshiba,
NEC P6 and P7 or compatible printersrequired for photo¬
ready traces. Also works on Hewlett/Packard plotters.
■ Package: Includes 100 page manual in 3-ring slipcase
binder and program diskette.
i
BFree phone support to registered users.
PCBoard Designer can dramatically improve design
I productivity by eliminating many redundant steps and
time-consuming alterations. With all of its advanced
| time-saving capabilities, PCBoard Designer pays for
| itself after the first successfully designed board.
Abacus Software, Inc.
5370 52nd St. S.E.
Grand Rapids, MI 49508
(616) 698-0330
PCBoard Designer
Suggested Retail Price:
$195.00
AUri ST, 52GST, 1040ST, TOS, ST BASIC and ST IjOOO are trademarks or registered trademarks of Atari Ccrp.
OEM is a registered trademark of Digital Research Inc.
Selected Abacus Products for the
PowerLedger ST
(formerly PowerPlan ST)
Spreadsheet/Graphics package
for the Atari ST
"A superior spreadsheet program for weekend
bookeeping to the heavyweight job costing appli¬
cations, (Powerledger ST) is a definite winner."
— Judi Lambert
ST World
Ever since VisiCalc and Lotus 1-2-3 stormed the
personal computer market, the computer has become an
important planning tool. PowerLedger ST brings the
power of electronic spreadsheets to the Atari ST line of
computers — it lets the user quickly perform hundreds of
calculations and "what-if' analyses for business
applications, and crunch raw data into meaningful,
comprehensible informadon, to keep track of budgets,
expenses and statistics.
PowerLedger ST is a powerful analysis package that
features a large spreadsheet (65,536 X 65,536
cells — over 4 billion data items). It also contains a
built-in calculator, online notepad, and integrated
graphics.
PowerLedger ST is also very easy to learn, since it uses
the familiar GEM features built into the ST. And
PowerLedger ST can use multiple windows — up to
seven. Data from the spreadsheet can be graphically
summarized in in pie charts, bar graphs and line charts,
and displayed simultaneously with the spreadsheet. For
example, one window can display part of the
spreadsheet; a second window a different part; and a third
window, a pie or bar chart of the data.
PowerLedger ST works hand-in-hand with our
DataTrieve data management package and our TextPro
wordprocessing package.
PowerLedger ST's extraordinary combination of data and
graphic power, ease of use and low price makes it a
perfect tool for every ST owner’s Financial planning
needs.
PowerLedger ST works with Atari ST systems with one
or more single- or double-sided disk drives. Works with
either monochrome or color ST monitors. Works with
most popular dot-matrix printers (optional).
PowerLedger ST Features:
• Familiar drop-down menus make PowerPlan easy to
learn and use
• Large capacity spreadsheet serves all the user's
analysis needs
• Convenient built-in notepad documents your
important memos
• Flexible online calculator gives you access to quick
computations
• Powerful options such as cut, copy and paste
operations speeds the user's work
• Integrated graphics summarize hundreds of data items
• Draws pie, bar, 3D bar, line and area charts
automatically (7 chart types)
• Multiple windows emphasize the user's analyses
• Accepts information from DataTrieve, our database
management software
• Passes data to TextPro wordprocessing package
• Capacities: maximum of 65,535 rows
maximum of 65,535 columns
variable column width
numeric precision of 14 digits
maximum value 1.797693 x l(p08
minimum value 2.2 x 10"-^
37 built-in functions
PowerLedger ST Suggested Retail Price: $79.95
Atari ST, 520ST, 1040ST, TDS, ST BASIC and ST LOGO are trademarks or registered trademarks of Atari Corp.
GEM is a registered trademark of Digital Research Inc.
Selected Abacus Products for the
TextPro
Wordprocessing package
for the Atari ST
"TextPro seems to be well thought out, easy, flexible
anf fast. The program makes excellent use of the GEM
interface and provides lots of small enhancements to
make your work go more easily. . . if you have an ST
and haven't moved up to a GEM word processor, pick
up this one and become a text pro.”
— John Kintz
ANTIC
"TextPro is the best wordprocessor available for the ST'
—Randy McSorley
Pacus Report
TextPro is a first-class word processor for the Atari ST
that boasts dozens of features for the writer. It was
designed by three writers to incorporate features that
they wanted in a wordprocessor — the result is a superior
package that suits the needs of all ST owners.
TextPro combines its "extra" features with easy
operation, flexibility, and speed — but at a very
reasonable price. The two-fingered typist will find
TextPro to be a friendly, user-oriented program, with all
the capabilities needed for fine writing and good-looking
printouts. Textpro offers full-screen editing with mouse
or keyboard shortcuts, as well as high-speed input,
scrolling and editing. TextPro includes a number of easy
to use formatting commands, fast and practical cursor
positioning and multiple text styles.
Two of TextPro's advanced features are automatic table
of contents generation and index generation
— capabilities usually found only on wordprocessing
packages costing hundreds of dollars. TextPro can also
print text horizontally (normal typewriter mode) or
vertically (sideways). For that professional newsletter
look, TextPro can print the text in columns — up to six
columns per page in sideways mode.
The user can write form letters using the convenient
Mail Merge option. TextPro also supports GEM-
oriented fonts and type styles — text can be bold,
underlined, italic , superscript^ etc., and in a
number of point sizes. TextPro even has advanced
features for the programmer for development with its
Non-document and C-sourcecode modes.
Suggested Retail Price: $49.95
• Full screen editing with either mouse or keyboard
• Automatic index generation
• Automatic table of contents generation
• Up to 30 user-defined function keys, max. 160
characters per key
• Lines up to 180 characters using horizontal scrolling
• Automatic hyphenation
• Automatic wordwrap
• Variable number of tab stops
• Multiple-column output (maximum 5 columns)
• Sideways printing on Epson FX and compatibles
• Performs mail merge and document chaining
• Flexible and adaptable printer driver
• Supports RS-232 file transfer (computer-to-computer
transfer possible)
• Detailed 65+ page manual
TextPro works with Atari ST systems with one or more
single- or double-sided disk drives. Works with either
monochrome or color ST monitors.
TexPro allows for flexible printer configurations with
most popular dot-matrix printers.
TextPro
Atari ST, 520ST, 1040ST,TOS, ST BASIC and ST LOGO are trademarks or registered trademarks of Atari Corp.
GEM is a registered trademark of Digital Research Inc.
INTERNALS GEM Programmer s Ref. TRICKS 4 TIPS GRAPHICS 4 SOUND BASIC Training Guide
Essential guide to learning the For serious programmers in Fantastic collection of pro- Detailed guide to understand- Indispensible handbook for
inside information of the ST. need of detailed information grams and info for the ST. ing graphics 4 sound on the beginning BASIC program-
Detailed descriptions of sound on GEM. Written with an Complete programs include: ST. 2D 4 3D function plotters. mere. Learn fundamentals of
& graphics chips, internal easy-to-understand format. All super-fast RAM disk; time- Moir6 patterns, various reso- programming. Flowcharting,
hardware, various ports, GEM. GEM examples are written in saving printer spooler; color lutions and graphic memory, numbering system, logical
Commented BIOS listing. An C and assembly. Required print hardcopy; plotter output fractals, waveform generation. operators, program structures,
indispensible reference for reading for the serious pro- hardcopy. Money saving tricks Examples written in C. LOGO, bits 4 bytes, disk use, chapter
your library. 450pp. $19.95 grammer. 450pp. $19.95 and tips. 200 pp. $19.95 BASIC and Mod ula2. $19.95 quizzes. 200pp. $16.95
PRESENTING THE ST MACHINE LANGUAGE LOGO PEEKS & POKES BEGINNER S GUIDE BASIC TO C
Gives you an in-depth Program in the fastest Take control of your Enhance your programs Finally a book for those If you are already familiar
look at this sensational language for your Atari ATARI ST by learning with the examples found new to the ST wanting to with BASIC, learning C
new computer. Discusses ST. Learn the 68000 LOGO-the easy-to-use, within this book. Explores understanding ST basics, will be all that much
the architecture of the assembly language, its yet powerful language, using the different lang- Thoroughly understand easier. Shows the trans-
ST, working with GEM, numbering system, use Topics covered include uages BASIC, C, LOGO your ST and its many jtion from a BASIC
the mouse, operating of registers, the structure structured programming, and machine language, devices. Learn the funda- program, translated step
system, all the various & important details of the graphic movement, file using various interlaces, mentals of BASIC, LOGO by step, to the final 6
interfaces, the 68000 instruction set, and use of handling and more. An memory usage, reading and more. Complete with program. For all users
chip and its instructions, the internal system excellent book for kids as and saving from and to index, glossary and illus- interested in taking the
LOGO. $16.95 routines. 280pp $19.95 well as adults. $19.95 disk, more. $16.95 trations. +200pp $16.95 nextstep. $19.95
Abacus
The ATARI logo and ATARI ST are kademarks of Atari Corp.
Software
5370 52nd Street SE Grand Rapids, Ml 49508 Phone (616) 698-0330
Optional diskettes are available for all book titles at $14.95
Call now for the name of your nearest dealer. Or order directly from ABACUS with your MasterCard, VISA, or Amex card. Add
$4.00 per order for postage and handling. Foreign add $10.00 per book. Other software and books coming soon. Call or
write for your free catalog. Dealer inquiries welcome-over 1400 dealers nationwide.
Send your completed order blank to:
How to Order
Abacus 5370 52nd Street SE Grand Rapids, Ml 49508
All of our ST products — applications and language software, and our
acclaimed 14 volume Atari ST Reference Library — are available at
more than 2000 dealers in the U.S. and Canada. To find out the
location of the Abacus dealer nearest to you, call:
(616) 698-0330
8:30 am-8:00 pm Eastern Standard Time
Or order from Abacus directly by phone with your credit card. We
accept Mastercard, Visa and American Express.
Every one of our software packages is backed by the Abacus 30-Day
Guaranteed for any reason you're not satisified by the software
purchased directly from us, simply return the prooduct for a full refund
of the purchase price.
Order Blank
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INTERNALS
This INTERNALS volume is a welcome addition to any ST
programmer's library. Inside you'll find important hardware and
programming information for your ST. Contains valuable
information for the professional programmer and ST novice.
Here is a short list of some of the things you can expect to read
about:
• 68000 processor
• WD 1 772 disk controller
• ACIA's 6850
• Centronics interface
• MIDI-interface
• GEMDOS
• Interrupt instructions
• BIOS listing
About the authors:
The authors, Klaus Gerits, Lothar Englisch and Rolf Bruckmann,
are all part of the experienced Data Becker Product
Development team, based in Duesseldorf, W. Germany. They
are all best selling computer book authors and very
knowledgable concerning the subjects presented in this book.
Custom chips
MFP 68901
YM-2149 sound generator
RS-232
DMA controller
BIOS &XBIOS
Error codes
Blitter chip
ISBN Q-Tlb43T-Mb-l
A Data Becker book published by
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